Fix the Ease expression of the Tween extension (#5810)

Don't show in changelog

.circleci/config.yml

@@ -62,9 +62,10 @@ jobs:
 
       # Build GDevelop IDE (seems like we need to allow Node.js to use more space than usual)
       # Note: Code signing is done using CSC_LINK (see https://www.electron.build/code-signing).
+      # To test signing the code in the CI, add "export CSC_FOR_PULL_REQUEST=true && " before the command.
       - run:
           name: Build GDevelop IDE
-          command: export NODE_OPTIONS="--max-old-space-size=7168" && cd newIDE/electron-app && CI=false npm run build -- --mac --publish=never
+          command: export CSC_FOR_PULL_REQUEST=true && export NODE_OPTIONS="--max-old-space-size=7168" && cd newIDE/electron-app && CI=false npm run build -- --mac --publish=never
 
       - run:
           name: Clean dist folder to keep only installers/binaries.

.github/workflows/extract-translations.yml

@@ -26,7 +26,7 @@ jobs:
         run: sudo apt update && sudo apt install gettext -y
 
       - name: Install newIDE dependencies
-        run: npm install
+        run: npm ci
         working-directory: newIDE/app
 
       - name: Extract translations

CMakeLists.txt

@@ -60,7 +60,7 @@ if("${CMAKE_BUILD_TYPE}" STREQUAL "Release" AND NOT WIN32 AND CMAKE_COMPILER_IS_
 endif()
 
 #Activate C++11
-set(CMAKE_CXX_STANDARD 11)
+set(CMAKE_CXX_STANDARD 11) # Upgrading to C++17 would need to remove usage of bind2nd (should be easy).
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 # Mark some warnings as errors
@@ -77,7 +77,8 @@ if(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
 		-Wno-unused-private-field
 
 		# Make as much warnings considered as errors as possible (only one for now).
-		-Werror=return-stack-address)
+		-Werror=return-stack-address
+		-Werror=return-type)
 endif()
 
 # Define common directories:

Core/GDCore/Events/Builtin/ForEachChildVariableEvent.cpp

@@ -45,10 +45,39 @@ ForEachChildVariableEvent::GetAllActionsVectors() const {
   return allActions;
 }
 
+vector<pair<gd::Expression*, gd::ParameterMetadata> >
+    ForEachChildVariableEvent::GetAllExpressionsWithMetadata() {
+  vector<pair<gd::Expression*, gd::ParameterMetadata> >
+      allExpressionsWithMetadata;
+  auto metadata = gd::ParameterMetadata().SetType("scenevar");
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&iterableVariableName, metadata));
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&valueIteratorVariableName, metadata));
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&keyIteratorVariableName, metadata));
+
+  return allExpressionsWithMetadata;
+}
+vector<pair<const gd::Expression*, const gd::ParameterMetadata> >
+    ForEachChildVariableEvent::GetAllExpressionsWithMetadata() const {
+  vector<pair<const gd::Expression*, const gd::ParameterMetadata> >
+      allExpressionsWithMetadata;
+  auto metadata = gd::ParameterMetadata().SetType("scenevar");
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&iterableVariableName, metadata));
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&valueIteratorVariableName, metadata));
+  allExpressionsWithMetadata.push_back(
+      std::make_pair(&keyIteratorVariableName, metadata));
+
+  return allExpressionsWithMetadata;
+}
+
 void ForEachChildVariableEvent::SerializeTo(SerializerElement& element) const {
-  element.AddChild("iterableVariableName").SetValue(iterableVariableName);
-  element.AddChild("valueIteratorVariableName").SetValue(valueIteratorVariableName);
-  element.AddChild("keyIteratorVariableName").SetValue(keyIteratorVariableName);
+  element.AddChild("iterableVariableName").SetValue(iterableVariableName.GetPlainString());
+  element.AddChild("valueIteratorVariableName").SetValue(valueIteratorVariableName.GetPlainString());
+  element.AddChild("keyIteratorVariableName").SetValue(keyIteratorVariableName.GetPlainString());
   gd::EventsListSerialization::SerializeInstructionsTo(
       conditions, element.AddChild("conditions"));
   gd::EventsListSerialization::SerializeInstructionsTo(

Core/GDCore/Events/Builtin/ForEachChildVariableEvent.h

@@ -8,6 +8,7 @@
 #define FOREACHCHILDVARIABLEEVENT_H
 #include "GDCore/Events/Event.h"
 #include "GDCore/Events/EventsList.h"
+#include "GDCore/Events/Expression.h"
 namespace gd {
 class Instruction;
 class Project;
@@ -44,7 +45,7 @@ class GD_CORE_API ForEachChildVariableEvent : public gd::BaseEvent {
    *
    * It is the structure variable that will be iterated on.
    */
-  const gd::String& GetIterableVariableName() const { return iterableVariableName; };
+  const gd::String& GetIterableVariableName() const { return iterableVariableName.GetPlainString(); };
 
   /**
    * \brief Set the iterable variable name attached to the event.
@@ -56,15 +57,15 @@ class GD_CORE_API ForEachChildVariableEvent : public gd::BaseEvent {
   /**
    * \brief Get the value iterator variable attached to the event.
    *
-   * It is the variable that will contain the value of the 
+   * It is the variable that will contain the value of the
    * iterable's child being iterated on.
    */
-  const gd::String& GetValueIteratorVariableName() const { return valueIteratorVariableName; };
+  const gd::String& GetValueIteratorVariableName() const { return valueIteratorVariableName.GetPlainString(); };
 
   /**
    * \brief Set the value iterator variable attached to the event.
    *
-   * It is the variable that will contain the value of the 
+   * It is the variable that will contain the value of the
    * iterable's child being iterated on.
    */
   void SetValueIteratorVariableName(gd::String newName) { valueIteratorVariableName = newName; };
@@ -72,15 +73,15 @@ class GD_CORE_API ForEachChildVariableEvent : public gd::BaseEvent {
   /**
    * \brief Get the key iterator variable attached to the event.
    *
-   * It is the variable that will contain the name of the 
+   * It is the variable that will contain the name of the
    * iterable's child being iterated on.
    */
-  const gd::String& GetKeyIteratorVariableName() const { return keyIteratorVariableName; };
+  const gd::String& GetKeyIteratorVariableName() const { return keyIteratorVariableName.GetPlainString(); };
 
   /**
    * \brief Set the key iterator variable attached to the event.
    *
-   * It is the variable that will contain the name of the 
+   * It is the variable that will contain the name of the
    * iterable's child being iterated on.
    */
   void SetKeyIteratorVariableName(gd::String newName) { keyIteratorVariableName = newName; };
@@ -92,14 +93,19 @@ class GD_CORE_API ForEachChildVariableEvent : public gd::BaseEvent {
   virtual std::vector<gd::InstructionsList*> GetAllConditionsVectors();
   virtual std::vector<gd::InstructionsList*> GetAllActionsVectors();
 
+  virtual std::vector<std::pair<const gd::Expression*, const gd::ParameterMetadata> >
+        GetAllExpressionsWithMetadata() const;
+  virtual std::vector<std::pair<gd::Expression*, gd::ParameterMetadata> >
+        GetAllExpressionsWithMetadata();
+
   virtual void SerializeTo(SerializerElement& element) const;
   virtual void UnserializeFrom(gd::Project& project,
                                const SerializerElement& element);
 
  private:
-  gd::String valueIteratorVariableName;
-  gd::String keyIteratorVariableName;
-  gd::String iterableVariableName;
+  gd::Expression valueIteratorVariableName;
+  gd::Expression keyIteratorVariableName;
+  gd::Expression iterableVariableName;
   gd::InstructionsList conditions;
   gd::InstructionsList actions;
   gd::EventsList events;

Core/GDCore/Events/Builtin/ForEachEvent.h

@@ -64,12 +64,6 @@ class GD_CORE_API ForEachEvent : public gd::BaseEvent {
   virtual void UnserializeFrom(gd::Project& project,
                                const SerializerElement& element);
 
-  std::vector<gd::Expression*> GetAllObjectExpressions() {
-    std::vector<gd::Expression*> allObjectExpressions;
-    allObjectExpressions.push_back(&objectsToPick);
-    return allObjectExpressions;
-  }
-
  private:
   gd::Expression objectsToPick;
   gd::InstructionsList conditions;

Core/GDCore/Events/Builtin/LinkEvent.cpp

@@ -131,30 +131,36 @@ void LinkEvent::SerializeTo(SerializerElement& element) const {
 
 void LinkEvent::UnserializeFrom(gd::Project& project,
                                 const SerializerElement& element) {
-  SerializerElement& includeElement = element.GetChild("include", 0, "Limites");
-
   SetTarget(element.GetChild("target", 0, "Scene").GetValue().GetString());
 
-  if (includeElement.HasAttribute("includeAll")) {
-    // Compatibility with GDevelop <= 4.0.92
-    if (includeElement.GetBoolAttribute("includeAll", true)) {
-      SetIncludeAllEvents();
+  // Compatibility with GD <= 5
+  if (element.HasChild("include", "Limites")) {
+    SerializerElement& includeElement = element.GetChild("include", 0, "Limites");
+    if (includeElement.HasAttribute("includeAll")) {
+      // Compatibility with GDevelop <= 4.0.92
+      if (includeElement.GetBoolAttribute("includeAll", true)) {
+        SetIncludeAllEvents();
+      } else {
+        SetIncludeStartAndEnd(includeElement.GetIntAttribute("start"),
+                              includeElement.GetIntAttribute("end"));
+      }
     } else {
-      SetIncludeStartAndEnd(includeElement.GetIntAttribute("start"),
-                            includeElement.GetIntAttribute("end"));
+      // GDevelop > 4.0.92
+      IncludeConfig config = static_cast<IncludeConfig>(
+          includeElement.GetIntAttribute("includeConfig", 0));
+      if (config == INCLUDE_ALL)
+        SetIncludeAllEvents();
+      else if (config == INCLUDE_EVENTS_GROUP)
+        SetIncludeEventsGroup(includeElement.GetStringAttribute("eventsGroup"));
+      else if (config == INCLUDE_BY_INDEX)
+        SetIncludeStartAndEnd(includeElement.GetIntAttribute("start"),
+                              includeElement.GetIntAttribute("end"));
     }
   } else {
-    // GDevelop > 4.0.92
-    IncludeConfig config = static_cast<IncludeConfig>(
-        includeElement.GetIntAttribute("includeConfig", 0));
-    if (config == INCLUDE_ALL)
-      SetIncludeAllEvents();
-    else if (config == INCLUDE_EVENTS_GROUP)
-      SetIncludeEventsGroup(includeElement.GetStringAttribute("eventsGroup"));
-    else if (config == INCLUDE_BY_INDEX)
-      SetIncludeStartAndEnd(includeElement.GetIntAttribute("start"),
-                            includeElement.GetIntAttribute("end"));
+    // Since GDevelop 5, links always include all events.
+    SetIncludeAllEvents();
   }
+  // end of compatibility code
 }
 
 bool LinkEvent::AcceptVisitor(gd::EventVisitor &eventVisitor) {

Core/GDCore/Events/Builtin/RepeatEvent.cpp

@@ -35,7 +35,7 @@ vector<pair<gd::Expression*, gd::ParameterMetadata> >
     RepeatEvent::GetAllExpressionsWithMetadata() {
   vector<pair<gd::Expression*, gd::ParameterMetadata> >
       allExpressionsWithMetadata;
-  auto metadata = gd::ParameterMetadata().SetType("expression");
+  auto metadata = gd::ParameterMetadata().SetType("number");
   allExpressionsWithMetadata.push_back(
       std::make_pair(&repeatNumberExpression, metadata));
 
@@ -61,7 +61,7 @@ vector<pair<const gd::Expression*, const gd::ParameterMetadata> >
     RepeatEvent::GetAllExpressionsWithMetadata() const {
   vector<pair<const gd::Expression*, const gd::ParameterMetadata> >
       allExpressionsWithMetadata;
-  auto metadata = gd::ParameterMetadata().SetType("expression");
+  auto metadata = gd::ParameterMetadata().SetType("number");
   allExpressionsWithMetadata.push_back(
       std::make_pair(&repeatNumberExpression, metadata));
 

Core/GDCore/Events/CodeGeneration/EventsCodeGenerator.cpp

@@ -16,6 +16,7 @@
 #include "GDCore/Extensions/PlatformExtension.h"
 #include "GDCore/Project/Layout.h"
 #include "GDCore/Project/ObjectsContainer.h"
+#include "GDCore/Project/ObjectsContainersList.h"
 #include "GDCore/Project/Project.h"
 
 using namespace std;
@@ -68,8 +69,36 @@ gd::String EventsCodeGenerator::GenerateRelationalOperatorCall(
     }
   }
 
-  return callStartString + "(" + argumentsStr + ") " + relationalOperator +
-         " " + rhs;
+  auto lhs = callStartString + "(" + argumentsStr + ")";
+  return GenerateRelationalOperation(relationalOperator, lhs, rhs);
+}
+
+/**
+ * @brief Generate a relational operation
+ * 
+ * @param relationalOperator the operator
+ * @param lhs the left hand operand
+ * @param rhs the right hand operand
+ * @return gd::String 
+ */
+gd::String EventsCodeGenerator::GenerateRelationalOperation(
+    const gd::String& relationalOperator,
+    const gd::String& lhs,
+    const gd::String& rhs) {
+  return lhs + " " + GenerateRelationalOperatorCodes(relationalOperator) + " " + rhs;
+}
+
+const gd::String EventsCodeGenerator::GenerateRelationalOperatorCodes(const gd::String &operatorString) {
+    if (operatorString == "=") {
+        return "==";
+    }
+    if (operatorString != "<" && operatorString != ">" &&
+        operatorString != "<=" && operatorString != ">=" && operatorString != "!=" &&
+        operatorString != "startsWith" && operatorString != "endsWith" && operatorString != "contains") {
+      cout << "Warning: Bad relational operator: Set to == by default." << endl;
+      return "==";
+    }
+    return operatorString;
 }
 
 /**
@@ -295,16 +324,10 @@ gd::String EventsCodeGenerator::GenerateConditionCode(
       gd::String objectInParameter =
           condition.GetParameter(pNb).GetPlainString();
 
-      if (!GetObjectsAndGroups().HasObjectNamed(objectInParameter) &&
-          !GetGlobalObjectsAndGroups().HasObjectNamed(objectInParameter) &&
-          !GetObjectsAndGroups().GetObjectGroups().Has(objectInParameter) &&
-          !GetGlobalObjectsAndGroups().GetObjectGroups().Has(
-              objectInParameter)) {
+      if (!GetObjectsContainersList().HasObjectOrGroupNamed(objectInParameter)) {
         return "/* Unknown object - skipped. */";
       } else if (!instrInfos.parameters[pNb].GetExtraInfo().empty() &&
-                 gd::GetTypeOfObject(GetGlobalObjectsAndGroups(),
-                                     GetObjectsAndGroups(),
-                                     objectInParameter) !=
+                GetObjectsContainersList().GetTypeOfObject(objectInParameter) !=
                      instrInfos.parameters[pNb].GetExtraInfo()) {
         return "/* Mismatched object type - skipped. */";
       }
@@ -315,11 +338,10 @@ gd::String EventsCodeGenerator::GenerateConditionCode(
     gd::String objectName = condition.GetParameter(0).GetPlainString();
     if (!objectName.empty() && !instrInfos.parameters.empty()) {
       std::vector<gd::String> realObjects =
-          ExpandObjectsName(objectName, context);
+          GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
       for (std::size_t i = 0; i < realObjects.size(); ++i) {
         // Set up the context
-        gd::String objectType = gd::GetTypeOfObject(
-            GetGlobalObjectsAndGroups(), GetObjectsAndGroups(), realObjects[i]);
+        gd::String objectType = GetObjectsContainersList().GetTypeOfObject(realObjects[i]);
         const ObjectMetadata& objInfo =
             MetadataProvider::GetObjectMetadata(platform, objectType);
 
@@ -343,13 +365,10 @@ gd::String EventsCodeGenerator::GenerateConditionCode(
     }
   } else if (instrInfos.IsBehaviorInstruction()) {
     gd::String objectName = condition.GetParameter(0).GetPlainString();
-    gd::String behaviorType =
-        gd::GetTypeOfBehavior(GetGlobalObjectsAndGroups(),
-                              GetObjectsAndGroups(),
-                              condition.GetParameter(1).GetPlainString());
+    gd::String behaviorType = GetObjectsContainersList().GetTypeOfBehavior(condition.GetParameter(1).GetPlainString());
     if (instrInfos.parameters.size() >= 2) {
       std::vector<gd::String> realObjects =
-          ExpandObjectsName(objectName, context);
+          GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
       for (std::size_t i = 0; i < realObjects.size(); ++i) {
         // Setup context
         const BehaviorMetadata& autoInfo =
@@ -479,16 +498,10 @@ gd::String EventsCodeGenerator::GenerateActionCode(
   for (std::size_t pNb = 0; pNb < instrInfos.parameters.size(); ++pNb) {
     if (ParameterMetadata::IsObject(instrInfos.parameters[pNb].GetType())) {
       gd::String objectInParameter = action.GetParameter(pNb).GetPlainString();
-      if (!GetObjectsAndGroups().HasObjectNamed(objectInParameter) &&
-          !GetGlobalObjectsAndGroups().HasObjectNamed(objectInParameter) &&
-          !GetObjectsAndGroups().GetObjectGroups().Has(objectInParameter) &&
-          !GetGlobalObjectsAndGroups().GetObjectGroups().Has(
-              objectInParameter)) {
+      if (!GetObjectsContainersList().HasObjectOrGroupNamed(objectInParameter)) {
         return "/* Unknown object - skipped. */";
       } else if (!instrInfos.parameters[pNb].GetExtraInfo().empty() &&
-                 gd::GetTypeOfObject(GetGlobalObjectsAndGroups(),
-                                     GetObjectsAndGroups(),
-                                     objectInParameter) !=
+                 GetObjectsContainersList().GetTypeOfObject(objectInParameter) !=
                      instrInfos.parameters[pNb].GetExtraInfo()) {
         return "/* Mismatched object type - skipped. */";
       }
@@ -501,11 +514,10 @@ gd::String EventsCodeGenerator::GenerateActionCode(
 
     if (!instrInfos.parameters.empty()) {
       std::vector<gd::String> realObjects =
-          ExpandObjectsName(objectName, context);
+          GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
       for (std::size_t i = 0; i < realObjects.size(); ++i) {
         // Setup context
-        gd::String objectType = gd::GetTypeOfObject(
-            GetGlobalObjectsAndGroups(), GetObjectsAndGroups(), realObjects[i]);
+        gd::String objectType = GetObjectsContainersList().GetTypeOfObject(realObjects[i]);
         const ObjectMetadata& objInfo =
             MetadataProvider::GetObjectMetadata(platform, objectType);
 
@@ -529,14 +541,11 @@ gd::String EventsCodeGenerator::GenerateActionCode(
     }
   } else if (instrInfos.IsBehaviorInstruction()) {
     gd::String objectName = action.GetParameter(0).GetPlainString();
-    gd::String behaviorType =
-        gd::GetTypeOfBehavior(GetGlobalObjectsAndGroups(),
-                              GetObjectsAndGroups(),
-                              action.GetParameter(1).GetPlainString());
+    gd::String behaviorType = GetObjectsContainersList().GetTypeOfBehavior(action.GetParameter(1).GetPlainString());
 
     if (instrInfos.parameters.size() >= 2) {
       std::vector<gd::String> realObjects =
-          ExpandObjectsName(objectName, context);
+          GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
       for (std::size_t i = 0; i < realObjects.size(); ++i) {
         // Setup context
         const BehaviorMetadata& autoInfo =
@@ -657,18 +666,6 @@ gd::String EventsCodeGenerator::GenerateActionsListCode(
   return outputCode;
 }
 
-const gd::String EventsCodeGenerator::GenerateRelationalOperatorCodes(const gd::String &operatorString) {
-    if (operatorString == "=") {
-        return "==";
-    }
-    if (operatorString != "<" && operatorString != ">" &&
-        operatorString != "<=" && operatorString != ">=" && operatorString != "!=") {
-      cout << "Warning: Bad relational operator: Set to == by default." << endl;
-      return "==";
-    }
-    return operatorString;
-}
-
 gd::String EventsCodeGenerator::GenerateParameterCodes(
     const gd::Expression& parameter,
     const gd::ParameterMetadata& metadata,
@@ -693,7 +690,7 @@ gd::String EventsCodeGenerator::GenerateParameterCodes(
     argOutput =
         GenerateObject(parameter.GetPlainString(), metadata.GetType(), context);
   } else if (metadata.GetType() == "relationalOperator") {
-    argOutput += GenerateRelationalOperatorCodes(parameter.GetPlainString());
+    argOutput += parameter.GetPlainString();
     argOutput = "\"" + argOutput + "\"";
   } else if (metadata.GetType() == "operator") {
     argOutput += parameter.GetPlainString();
@@ -912,41 +909,6 @@ gd::String EventsCodeGenerator::ConvertToStringExplicit(
   return "\"" + ConvertToString(plainString) + "\"";
 }
 
-std::vector<gd::String> EventsCodeGenerator::ExpandObjectsName(
-    const gd::String& objectName,
-    const EventsCodeGenerationContext& context) const {
-  // Note: this logic is duplicated in EventsContextAnalyzer::ExpandObjectsName
-  std::vector<gd::String> realObjects;
-  if (globalObjectsAndGroups.GetObjectGroups().Has(objectName))
-    realObjects = globalObjectsAndGroups.GetObjectGroups()
-                      .Get(objectName)
-                      .GetAllObjectsNames();
-  else if (objectsAndGroups.GetObjectGroups().Has(objectName))
-    realObjects =
-        objectsAndGroups.GetObjectGroups().Get(objectName).GetAllObjectsNames();
-  else
-    realObjects.push_back(objectName);
-
-  // If current object is present, use it and only it.
-  if (find(realObjects.begin(),
-           realObjects.end(),
-           context.GetCurrentObject()) != realObjects.end()) {
-    realObjects.clear();
-    realObjects.push_back(context.GetCurrentObject());
-  }
-
-  // Ensure that all returned objects actually exists.
-  for (std::size_t i = 0; i < realObjects.size();) {
-    if (!objectsAndGroups.HasObjectNamed(realObjects[i]) &&
-        !globalObjectsAndGroups.HasObjectNamed(realObjects[i]))
-      realObjects.erase(realObjects.begin() + i);
-    else
-      ++i;
-  }
-
-  return realObjects;
-}
-
 void EventsCodeGenerator::DeleteUselessEvents(gd::EventsList& events) {
   for (std::size_t eId = events.size() - 1; eId < events.size(); --eId) {
     if (events[eId].CanHaveSubEvents())  // Process sub events, if any
@@ -963,6 +925,8 @@ void EventsCodeGenerator::DeleteUselessEvents(gd::EventsList& events) {
  */
 void EventsCodeGenerator::PreprocessEventList(gd::EventsList& listEvent) {
   for (std::size_t i = 0; i < listEvent.GetEventsCount(); ++i) {
+    if (listEvent[i].IsDisabled()) continue;
+
     listEvent[i].Preprocess(*this, listEvent, i);
     if (i <
         listEvent.GetEventsCount()) {  // Be sure that that there is still an
@@ -1260,12 +1224,24 @@ gd::String EventsCodeGenerator::GenerateArgumentsList(
   return argumentsStr;
 }
 
+gd::String EventsCodeGenerator::GeneratePropertyGetter(const gd::PropertiesContainer& propertiesContainer,
+                                                       const gd::NamedPropertyDescriptor& property,
+                                                       const gd::String& type,
+                                                       gd::EventsCodeGenerationContext& context) {
+  return "getProperty" + property.GetName() + "As" + type + "()";
+}
+
+gd::String EventsCodeGenerator::GenerateParameterGetter(const gd::ParameterMetadata& parameter,
+                                                        const gd::String& type,
+                                                        gd::EventsCodeGenerationContext& context) {
+  return "getParameter" + parameter.GetName() + "As" + type + "()";
+}
+
 EventsCodeGenerator::EventsCodeGenerator(const gd::Project& project_,
                                          const gd::Layout& layout,
                                          const gd::Platform& platform_)
     : platform(platform_),
-      globalObjectsAndGroups(project_),
-      objectsAndGroups(layout),
+      projectScopedContainers(gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project_, layout)),
       hasProjectAndLayout(true),
       project(&project_),
       scene(&layout),
@@ -1277,11 +1253,9 @@ EventsCodeGenerator::EventsCodeGenerator(const gd::Project& project_,
 
 EventsCodeGenerator::EventsCodeGenerator(
     const gd::Platform& platform_,
-    const gd::ObjectsContainer& globalObjectsAndGroups_,
-    const gd::ObjectsContainer& objectsAndGroups_)
+    const gd::ProjectScopedContainers& projectScopedContainers_)
     : platform(platform_),
-      globalObjectsAndGroups(globalObjectsAndGroups_),
-      objectsAndGroups(objectsAndGroups_),
+      projectScopedContainers(projectScopedContainers_),
       hasProjectAndLayout(false),
       project(nullptr),
       scene(nullptr),

Core/GDCore/Events/CodeGeneration/EventsCodeGenerator.h

@@ -12,6 +12,7 @@
 
 #include "GDCore/Events/Event.h"
 #include "GDCore/Events/Instruction.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/String.h"
 namespace gd {
 class EventsList;
@@ -19,6 +20,7 @@ class Expression;
 class Project;
 class Layout;
 class ObjectsContainer;
+class ObjectsContainersList;
 class ExternalEvents;
 class ParameterMetadata;
 class ObjectMetadata;
@@ -56,9 +58,9 @@ class GD_CORE_API EventsCodeGenerator {
    * \brief Construct a code generator for the specified
    * objects/groups and platform
    */
-  EventsCodeGenerator(const gd::Platform& platform,
-                      const gd::ObjectsContainer& globalObjectsAndGroups_,
-                      const gd::ObjectsContainer& objectsAndGroups_);
+  EventsCodeGenerator(
+      const gd::Platform& platform,
+      const gd::ProjectScopedContainers& projectScopedContainers_);
   virtual ~EventsCodeGenerator(){};
 
   /**
@@ -326,18 +328,12 @@ class GD_CORE_API EventsCodeGenerator {
    */
   bool ErrorOccurred() const { return errorOccurred; };
 
-  /**
-   * \brief Get the global objects/groups used for code generation.
-   */
-  const gd::ObjectsContainer& GetGlobalObjectsAndGroups() const {
-    return globalObjectsAndGroups;
-  }
+  const gd::ObjectsContainersList& GetObjectsContainersList() const {
+    return projectScopedContainers.GetObjectsContainersList();
+  };
 
-  /**
-   * \brief Get the objects/groups used for code generation.
-   */
-  const gd::ObjectsContainer& GetObjectsAndGroups() const {
-    return objectsAndGroups;
+  const gd::ProjectScopedContainers& GetProjectScopedContainers() const {
+    return projectScopedContainers;
   }
 
   /**
@@ -363,22 +359,6 @@ class GD_CORE_API EventsCodeGenerator {
    */
   const gd::Platform& GetPlatform() const { return platform; }
 
-  /**
-   * \brief Convert a group name to the full list of objects contained in the
-   * group.
-   *
-   * Get a list containing the "real" objects name when the events refers to \a
-   * objectName :<br> If \a objectName is really an object, the list will only
-   * contains \a objectName unchanged.<br> If \a objectName is a group, the list
-   * will contains all the objects of the group.<br> If \a objectName is the
-   * "current" object in the context ( i.e: The object being used for launching
-   * an action... ), none of the two rules below apply, and the list will only
-   * contains the context "current" object name.
-   */
-  std::vector<gd::String> ExpandObjectsName(
-      const gd::String& objectName,
-      const EventsCodeGenerationContext& context) const;
-
   /**
    * \brief Get the maximum depth of custom conditions reached during code
    * generation.
@@ -493,10 +473,15 @@ class GD_CORE_API EventsCodeGenerator {
    */
   size_t GenerateSingleUsageUniqueIdForEventsList();
 
+  virtual gd::String GenerateRelationalOperation(
+      const gd::String& relationalOperator,
+      const gd::String& lhs,
+      const gd::String& rhs);
+
+ protected:
   virtual const gd::String GenerateRelationalOperatorCodes(
       const gd::String& operatorString);
 
- protected:
   /**
    * \brief Generate the code for a single parameter.
    *
@@ -566,6 +551,12 @@ class GD_CORE_API EventsCodeGenerator {
     return ".getChild(" + ConvertToStringExplicit(childName) + ")";
   };
 
+  virtual gd::String GenerateVariableValueAs(const gd::String& type) {
+    return type == "number|string" ? ".getAsNumberOrString()"
+           : type == "string"      ? ".getAsString()"
+                                   : ".getAsNumber()";
+  }
+
   /**
    * \brief Generate the code to get the child of a variable,
    * using generated the expression.
@@ -594,6 +585,17 @@ class GD_CORE_API EventsCodeGenerator {
     return "fakeObjectListOf_" + objectName;
   }
 
+  virtual gd::String GeneratePropertyGetter(
+      const gd::PropertiesContainer& propertiesContainer,
+      const gd::NamedPropertyDescriptor& property,
+      const gd::String& type,
+      gd::EventsCodeGenerationContext& context);
+
+  virtual gd::String GenerateParameterGetter(
+      const gd::ParameterMetadata& parameter,
+      const gd::String& type,
+      gd::EventsCodeGenerationContext& context);
+
   /**
    * \brief Generate the code to reference an object which is
    * in an empty/null state.
@@ -673,7 +675,8 @@ class GD_CORE_API EventsCodeGenerator {
    * The default implementation generates C-style code : It wraps the predicate
    * inside parenthesis and add a !.
    */
-  virtual gd::String GenerateNegatedPredicate(const gd::String& predicate) const {
+  virtual gd::String GenerateNegatedPredicate(
+      const gd::String& predicate) const {
     return "!(" + predicate + ")";
   };
 
@@ -734,6 +737,7 @@ class GD_CORE_API EventsCodeGenerator {
       const std::vector<gd::String>& arguments,
       const gd::String& callStartString,
       std::size_t startFromArgument = 0);
+
   gd::String GenerateOperatorCall(const gd::InstructionMetadata& instrInfos,
                                   const std::vector<gd::String>& arguments,
                                   const gd::String& callStartString,
@@ -777,8 +781,7 @@ class GD_CORE_API EventsCodeGenerator {
 
   const gd::Platform& platform;  ///< The platform being used.
 
-  const gd::ObjectsContainer& globalObjectsAndGroups;
-  const gd::ObjectsContainer& objectsAndGroups;
+  gd::ProjectScopedContainers projectScopedContainers;
 
   bool hasProjectAndLayout;  ///< true only if project and layout are valid
                              ///< references. If false, they should not be used.

Core/GDCore/Events/CodeGeneration/ExpressionCodeGenerator.cpp

@@ -7,6 +7,7 @@
 
 #include <memory>
 #include <vector>
+#include <vector>
 
 #include "GDCore/CommonTools.h"
 #include "GDCore/Events/CodeGeneration/EventsCodeGenerationContext.h"
@@ -25,6 +26,9 @@
 #include "GDCore/IDE/Events/ExpressionValidator.h"
 #include "GDCore/Project/Layout.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/VariablesContainersList.h"
+#include "GDCore/Project/ObjectsContainersList.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/IDE/Events/ExpressionTypeFinder.h"
 #include "GDCore/IDE/Events/ExpressionVariableOwnerFinder.h"
 
@@ -47,8 +51,7 @@ gd::String ExpressionCodeGenerator::GenerateExpressionCode(
   }
 
   gd::ExpressionValidator validator(codeGenerator.GetPlatform(),
-                                    codeGenerator.GetGlobalObjectsAndGroups(),
-                                    codeGenerator.GetObjectsAndGroups(),
+                                    codeGenerator.GetProjectScopedContainers(),
                                     rootType);
   node->Visit(validator);
   if (!validator.GetFatalErrors().empty()) {
@@ -100,35 +103,95 @@ void ExpressionCodeGenerator::OnVisitVariableNode(VariableNode& node) {
   // This "translation" from the type to an enum could be avoided
   // if all types were moved to an enum.
   auto type = gd::ExpressionTypeFinder::GetType(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetProjectScopedContainers(),
                                             rootType,
                                             node);
-  EventsCodeGenerator::VariableScope scope =
-      type == "globalvar"
-          ? gd::EventsCodeGenerator::PROJECT_VARIABLE
-          : ((type == "scenevar")
-                 ? gd::EventsCodeGenerator::LAYOUT_VARIABLE
-                 : gd::EventsCodeGenerator::OBJECT_VARIABLE);
-  auto objectName = gd::ExpressionVariableOwnerFinder::GetObjectName(codeGenerator.GetPlatform(),
-                                        codeGenerator.GetGlobalObjectsAndGroups(),
-                                        codeGenerator.GetObjectsAndGroups(),
-                                        rootObjectName,
-                                        node);
-  output += codeGenerator.GenerateGetVariable(
-      node.name, scope, context, objectName);
-  if (node.child) node.child->Visit(*this);
+
+  if (gd::ParameterMetadata::IsExpression("variable", type)) {
+    // The node is a variable inside an expression waiting for a *variable* to be returned, not its value.
+    EventsCodeGenerator::VariableScope scope =
+        type == "globalvar"
+            ? gd::EventsCodeGenerator::PROJECT_VARIABLE
+            : ((type == "scenevar")
+                  ? gd::EventsCodeGenerator::LAYOUT_VARIABLE
+                  : gd::EventsCodeGenerator::OBJECT_VARIABLE);
+
+    auto objectName = gd::ExpressionVariableOwnerFinder::GetObjectName(codeGenerator.GetPlatform(),
+                                          codeGenerator.GetObjectsContainersList(),
+                                          rootObjectName,
+                                          node);
+    output += codeGenerator.GenerateGetVariable(
+        node.name, scope, context, objectName);
+    if (node.child) node.child->Visit(*this);
+  } else {
+    // The node represents a variable or an object variable in an expression waiting for its *value* to be returned.
+
+    codeGenerator.GetProjectScopedContainers().MatchIdentifierWithName<void>(node.name, [&](){
+      // Generate the code to access the object variables.
+
+      // Defer generation of the access to the object and variable to the child,
+      // once we know the name of the variable.
+      objectNameToUseForVariableAccessor = node.name;
+      if (node.child) node.child->Visit(*this);
+      objectNameToUseForVariableAccessor = "";
+
+      output += codeGenerator.GenerateVariableValueAs(type);
+    }, [&]() {
+      if (!codeGenerator.HasProjectAndLayout()) {
+        gd::LogWarning("Tried to generate access to a variable without a project/scene - the code generator only works for global and scene variables for now.");
+        output += GenerateDefaultValue(type);
+        return;
+      }
+
+      // This could be adapted in the future if more scopes are supported.
+      EventsCodeGenerator::VariableScope scope = gd::EventsCodeGenerator::PROJECT_VARIABLE;
+      if (codeGenerator.GetProjectScopedContainers().GetVariablesContainersList().GetBottomMostVariablesContainer()->Has(node.name)) {
+        scope = gd::EventsCodeGenerator::LAYOUT_VARIABLE;
+      }
+
+      output += codeGenerator.GenerateGetVariable(node.name, scope, context, "");
+      if (node.child) node.child->Visit(*this);
+      output += codeGenerator.GenerateVariableValueAs(type);
+    }, [&]() {
+      // Properties are not supported.
+      output += GenerateDefaultValue(type);
+    }, [&]() {
+      // Parameters are not supported.
+      output += GenerateDefaultValue(type);
+    }, [&]() {
+      // The identifier does not represents a variable (or a child variable), or not at least an existing
+      // one, nor an object variable. It's invalid.
+      output += GenerateDefaultValue(type);
+    });
+  }
 }
 
 void ExpressionCodeGenerator::OnVisitVariableAccessorNode(
     VariableAccessorNode& node) {
-  output += codeGenerator.GenerateVariableAccessor(node.name);
+    if (!objectNameToUseForVariableAccessor.empty()) {
+      // Use the name of the object passed by the parent, as we need both to access an object variable.
+      output += codeGenerator.GenerateGetVariable(node.name,
+          gd::EventsCodeGenerator::OBJECT_VARIABLE, context, objectNameToUseForVariableAccessor);
+
+      // We have accessed an object variable, from now we can continue accessing the child variables
+      // (including using the bracket notation).
+      objectNameToUseForVariableAccessor = "";
+    } else {
+        output += codeGenerator.GenerateVariableAccessor(node.name);
+    }
   if (node.child) node.child->Visit(*this);
 }
 
 void ExpressionCodeGenerator::OnVisitVariableBracketAccessorNode(
     VariableBracketAccessorNode& node) {
-  ExpressionCodeGenerator generator("string", "", codeGenerator, context);
+  if (!objectNameToUseForVariableAccessor.empty()) {
+    // Bracket notation can't be used to directly access a variable of an object (`MyObject["MyVariable"]`).
+    // This would be rejected by the ExpressionValidator.
+    output += codeGenerator.GenerateBadVariable();
+    return;
+  }
+
+  ExpressionCodeGenerator generator("number|string", "", codeGenerator, context);
   node.expression->Visit(generator);
   output +=
       codeGenerator.GenerateVariableBracketAccessor(generator.GetOutput());
@@ -137,10 +200,10 @@ void ExpressionCodeGenerator::OnVisitVariableBracketAccessorNode(
 
 void ExpressionCodeGenerator::OnVisitIdentifierNode(IdentifierNode& node) {
   auto type = gd::ExpressionTypeFinder::GetType(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetProjectScopedContainers(),
                                             rootType,
                                             node);
+
   if (gd::ParameterMetadata::IsObject(type)) {
     output +=
         codeGenerator.GenerateObject(node.identifierName, type, context);
@@ -153,8 +216,7 @@ void ExpressionCodeGenerator::OnVisitIdentifierNode(IdentifierNode& node) {
                     : gd::EventsCodeGenerator::OBJECT_VARIABLE);
 
       auto objectName = gd::ExpressionVariableOwnerFinder::GetObjectName(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetObjectsContainersList(),
                                             rootObjectName,
                                             node);
       output += codeGenerator.GenerateGetVariable(
@@ -162,30 +224,60 @@ void ExpressionCodeGenerator::OnVisitIdentifierNode(IdentifierNode& node) {
       if (!node.childIdentifierName.empty()) {
         output += codeGenerator.GenerateVariableAccessor(node.childIdentifierName);
       }
-  } else if (node.childIdentifierName.empty()) {
-    output += "/* Error during generation, unrecognized identifier type: " +
-              codeGenerator.ConvertToString(type) + " with value " +
-              codeGenerator.ConvertToString(node.identifierName) + " */ " +
-              codeGenerator.ConvertToStringExplicit(node.identifierName);
-  }
-  else {
-    // This is for function names that are put in IdentifierNode
-    // because the type is needed to tell them apart from variables.
-    output += GenerateDefaultValue(type);
+  } else {
+    const auto& variablesContainersList = codeGenerator.GetProjectScopedContainers().GetVariablesContainersList();
+    const auto& propertiesContainersList = codeGenerator.GetProjectScopedContainers().GetPropertiesContainersList();
+    const auto& parametersVectorsList = codeGenerator.GetProjectScopedContainers().GetParametersVectorsList();
+
+    // The node represents a variable, property, parameter or an object.
+    codeGenerator.GetProjectScopedContainers().MatchIdentifierWithName<void>(node.identifierName, [&]() {
+      // Generate the code to access the object variable.
+      output += codeGenerator.GenerateGetVariable(
+        node.childIdentifierName, gd::EventsCodeGenerator::OBJECT_VARIABLE, context, node.identifierName);
+      output += codeGenerator.GenerateVariableValueAs(type);
+    }, [&]() {
+      if (!codeGenerator.HasProjectAndLayout()) {
+        gd::LogWarning("Tried to generate access to a variable without a project/scene - the code generator only works for global and scene variables for now.");
+        output += GenerateDefaultValue(type);
+        return;
+      }
+
+      // This could be adapted in the future if more scopes are supported at runtime.
+      EventsCodeGenerator::VariableScope scope = gd::EventsCodeGenerator::PROJECT_VARIABLE;
+      if (variablesContainersList.GetBottomMostVariablesContainer()->Has(node.identifierName)) {
+        scope = gd::EventsCodeGenerator::LAYOUT_VARIABLE;
+      }
+
+      output += codeGenerator.GenerateGetVariable(node.identifierName, scope, context, "");
+      if (!node.childIdentifierName.empty()) {
+        output += codeGenerator.GenerateVariableAccessor(node.childIdentifierName);
+      }
+      output += codeGenerator.GenerateVariableValueAs(type);
+    }, [&]() {
+      const auto& propertiesContainerAndProperty = propertiesContainersList.Get(node.identifierName);
+
+      output += codeGenerator.GeneratePropertyGetter(
+        propertiesContainerAndProperty.first, propertiesContainerAndProperty.second, type, context);
+    }, [&]() {
+      const auto& parameter = gd::ParameterMetadataTools::Get(parametersVectorsList, node.identifierName);
+      output += codeGenerator.GenerateParameterGetter(parameter, type, context);
+    }, [&]() {
+      // The identifier does not represents a variable (or a child variable), or not at least an existing
+      // one, nor an object variable. It's invalid.
+      output += GenerateDefaultValue(type);
+    });
   }
 }
 
 void ExpressionCodeGenerator::OnVisitFunctionCallNode(FunctionCallNode& node) {
   auto type = gd::ExpressionTypeFinder::GetType(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetProjectScopedContainers(),
                                             rootType,
                                             node);
 
   const gd::ExpressionMetadata &metadata = MetadataProvider::GetFunctionCallMetadata(
       codeGenerator.GetPlatform(),
-      codeGenerator.GetGlobalObjectsAndGroups(),
-      codeGenerator.GetObjectsAndGroups(),
+      codeGenerator.GetObjectsContainersList(),
       node);
 
   if (gd::MetadataProvider::IsBadExpressionMetadata(metadata)) {
@@ -236,11 +328,6 @@ gd::String ExpressionCodeGenerator::GenerateObjectFunctionCode(
     const gd::String& objectName,
     const std::vector<std::unique_ptr<ExpressionNode>>& parameters,
     const ExpressionMetadata& expressionMetadata) {
-  const gd::ObjectsContainer& globalObjectsAndGroups =
-      codeGenerator.GetGlobalObjectsAndGroups();
-  const gd::ObjectsContainer& objectsAndGroups =
-      codeGenerator.GetObjectsAndGroups();
-
   codeGenerator.AddIncludeFiles(
       expressionMetadata.GetIncludeFiles());
 
@@ -261,12 +348,11 @@ gd::String ExpressionCodeGenerator::GenerateObjectFunctionCode(
 
   // Get object(s) concerned by function call
   std::vector<gd::String> realObjects =
-      codeGenerator.ExpandObjectsName(objectName, context);
+      codeGenerator.GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
   for (std::size_t i = 0; i < realObjects.size(); ++i) {
     context.ObjectsListNeeded(realObjects[i]);
 
-    gd::String objectType = gd::GetTypeOfObject(
-        globalObjectsAndGroups, objectsAndGroups, realObjects[i]);
+    gd::String objectType = codeGenerator.GetObjectsContainersList().GetTypeOfObject(realObjects[i]);
     const ObjectMetadata& objInfo = MetadataProvider::GetObjectMetadata(
         codeGenerator.GetPlatform(), objectType);
 
@@ -288,11 +374,6 @@ gd::String ExpressionCodeGenerator::GenerateBehaviorFunctionCode(
     const gd::String& behaviorName,
     const std::vector<std::unique_ptr<ExpressionNode>>& parameters,
     const ExpressionMetadata& expressionMetadata) {
-  const gd::ObjectsContainer& globalObjectsAndGroups =
-      codeGenerator.GetGlobalObjectsAndGroups();
-  const gd::ObjectsContainer& objectsAndGroups =
-      codeGenerator.GetObjectsAndGroups();
-
   codeGenerator.AddIncludeFiles(
       expressionMetadata.GetIncludeFiles());
 
@@ -311,12 +392,11 @@ gd::String ExpressionCodeGenerator::GenerateBehaviorFunctionCode(
 
   // Get object(s) concerned by function call
   std::vector<gd::String> realObjects =
-      codeGenerator.ExpandObjectsName(objectName, context);
+      codeGenerator.GetObjectsContainersList().ExpandObjectName(objectName, context.GetCurrentObject());
 
   gd::String functionOutput = GenerateDefaultValue(type);
 
-  gd::String behaviorType = gd::GetTypeOfBehavior(
-      globalObjectsAndGroups, objectsAndGroups, behaviorName);
+  gd::String behaviorType = codeGenerator.GetObjectsContainersList().GetTypeOfBehavior(behaviorName);
   const BehaviorMetadata& autoInfo = MetadataProvider::GetBehaviorMetadata(
       codeGenerator.GetPlatform(), behaviorType);
 
@@ -352,8 +432,7 @@ gd::String ExpressionCodeGenerator::GenerateParametersCodes(
     if (!parameterMetadata.IsCodeOnly()) {
       if (nonCodeOnlyParameterIndex < parameters.size()) {
         auto objectName = gd::ExpressionVariableOwnerFinder::GetObjectName(codeGenerator.GetPlatform(),
-                                              codeGenerator.GetGlobalObjectsAndGroups(),
-                                              codeGenerator.GetObjectsAndGroups(),
+                                              codeGenerator.GetObjectsContainersList(),
                                               rootObjectName,
                                               *parameters[nonCodeOnlyParameterIndex].get());
         ExpressionCodeGenerator generator(parameterMetadata.GetType(), objectName, codeGenerator, context);
@@ -423,8 +502,7 @@ gd::String ExpressionCodeGenerator::GenerateDefaultValue(
 
 void ExpressionCodeGenerator::OnVisitEmptyNode(EmptyNode& node) {
   auto type = gd::ExpressionTypeFinder::GetType(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetProjectScopedContainers(),
                                             rootType,
                                             node);
   output += GenerateDefaultValue(type);
@@ -433,8 +511,7 @@ void ExpressionCodeGenerator::OnVisitEmptyNode(EmptyNode& node) {
 void ExpressionCodeGenerator::OnVisitObjectFunctionNameNode(
     ObjectFunctionNameNode& node) {
   auto type = gd::ExpressionTypeFinder::GetType(codeGenerator.GetPlatform(),
-                                            codeGenerator.GetGlobalObjectsAndGroups(),
-                                            codeGenerator.GetObjectsAndGroups(),
+                                            codeGenerator.GetProjectScopedContainers(),
                                             rootType,
                                             node);
   output += GenerateDefaultValue(type);

Core/GDCore/Events/CodeGeneration/ExpressionCodeGenerator.h

@@ -102,6 +102,7 @@ class GD_CORE_API ExpressionCodeGenerator : public ExpressionParser2NodeWorker {
       const std::vector<std::unique_ptr<ExpressionNode>>& parameters);
 
   gd::String output;
+  gd::String objectNameToUseForVariableAccessor;
   EventsCodeGenerator& codeGenerator;
   EventsCodeGenerationContext& context;
   const gd::String rootType;

Core/GDCore/Events/Event.h

@@ -240,7 +240,7 @@ class GD_CORE_API BaseEvent {
    */
   virtual void UnserializeFrom(gd::Project& project,
                                const SerializerElement& element){};
-  
+
   virtual bool AcceptVisitor(gd::EventVisitor& eventVisitor);
   virtual void AcceptVisitor(gd::ReadOnlyEventVisitor& eventVisitor) const;
   ///@}
@@ -281,15 +281,6 @@ class GD_CORE_API BaseEvent {
    * \brief True if the event should be folded in the events editor.
    */
   bool IsFolded() const { return folded; }
-
-  /**
-   * \brief Return a list of all objects linked to the event.
-   */
-  virtual std::vector<gd::Expression*> GetAllObjectExpressions() {
-    std::vector<gd::Expression*> allObjectExpressions;
-    return allObjectExpressions;
-  }
-
   ///@}
 
   std::weak_ptr<gd::BaseEvent>

Core/GDCore/Events/Parsers/ExpressionParser2.h

@@ -47,14 +47,9 @@ class GD_CORE_API ExpressionParser2 {
   virtual ~ExpressionParser2(){};
 
   /**
-   * Parse the given expression with the specified type.
+   * Parse the given expression into a tree of nodes.
    *
-   * \param type Type of the expression: "string", "number",
-   * type supported by gd::ParameterMetadata::IsObject, types supported by
-   * gd::ParameterMetadata::IsExpression or "unknown".
-   * \param expression The expression to parse
-   * \param objectName Specify the object name, only for the
-   * case of "objectvar" type.
+   * \param expression The expression to parse.
    *
    * \return The node representing the expression as a parsed tree.
    */
@@ -267,12 +262,11 @@ class GD_CORE_API ExpressionParser2 {
     } else if (CheckIfChar(IsDot)) {
       ExpressionParserLocation dotLocation = SkipChar();
       SkipAllWhitespaces();
-      return ObjectFunctionOrBehaviorFunction(
+      return ObjectFunctionOrBehaviorFunctionOrVariable(
           name, nameLocation, dotLocation);
     } else if (CheckIfChar(IsOpeningSquareBracket)) {
       return Variable(name, nameLocation);
-    }
-    else {
+    } else {
       auto identifier = gd::make_unique<IdentifierNode>(name);
       identifier->location = ExpressionParserLocation(
           nameLocation.GetStartPosition(), GetCurrentPosition());
@@ -318,7 +312,7 @@ class GD_CORE_API ExpressionParser2 {
       auto dotLocation = SkipChar();
       SkipAllWhitespaces();
 
-      auto identifierAndLocation = ReadIdentifierName();
+      auto identifierAndLocation = ReadIdentifierName(/*allowDeprecatedSpacesInName=*/ false);
       auto child =
           gd::make_unique<VariableAccessorNode>(identifierAndLocation.name);
       child->child = VariableAccessorOrVariableBracketAccessor();
@@ -358,11 +352,11 @@ class GD_CORE_API ExpressionParser2 {
   }
 
   std::unique_ptr<IdentifierOrFunctionCallOrObjectFunctionNameOrEmptyNode>
-  ObjectFunctionOrBehaviorFunction(
+  ObjectFunctionOrBehaviorFunctionOrVariable(
       const gd::String &parentIdentifier,
       const ExpressionParserLocation &parentIdentifierLocation,
       const ExpressionParserLocation &parentIdentifierDotLocation) {
-    auto childIdentifierAndLocation = ReadIdentifierName();
+    auto childIdentifierAndLocation = ReadIdentifierName(/*allowDeprecatedSpacesInName=*/ false);
     const gd::String &childIdentifierName = childIdentifierAndLocation.name;
     const auto &childIdentifierNameLocation =
         childIdentifierAndLocation.location;
@@ -420,12 +414,6 @@ class GD_CORE_API ExpressionParser2 {
 
     auto node = gd::make_unique<IdentifierNode>(
         parentIdentifier, childIdentifierName);
-    if (!CheckIfChar(IsParameterSeparator) && !CheckIfChar(IsClosingParenthesis) && !IsEndReached()) {
-      node->diagnostic = RaiseSyntaxError(
-          _("An opening parenthesis (for an object expression), a double colon "
-            "(:: for a behavior expression), a dot or an opening bracket (for "
-            "a child variable) where expected."));
-    }
     node->location = ExpressionParserLocation(
         parentIdentifierLocation.GetStartPosition(), GetCurrentPosition());
     node->identifierNameLocation = parentIdentifierLocation;
@@ -625,13 +613,13 @@ class GD_CORE_API ExpressionParser2 {
     ExpressionParserLocation location;
   };
 
-  IdentifierAndLocation ReadIdentifierName() {
+  IdentifierAndLocation ReadIdentifierName(bool allowDeprecatedSpacesInName = true) {
     gd::String name;
     size_t startPosition = currentPosition;
     while (currentPosition < expression.size() &&
            (CheckIfChar(IsAllowedInIdentifier)
             // Allow whitespace in identifier name for compatibility
-            || expression[currentPosition] == ' ')) {
+            || (allowDeprecatedSpacesInName && expression[currentPosition] == ' '))) {
       name += expression[currentPosition];
       currentPosition++;
     }

Core/GDCore/Events/Parsers/ExpressionParser2Node.h

@@ -189,7 +189,7 @@ struct GD_CORE_API IdentifierOrFunctionCallOrObjectFunctionNameOrEmptyNode
  *
  * The name of a function to call on an object or the behavior,
  * for example: "MyObject.Function" or "MyObject.Physics".
- * 
+ *
  * A variable, potentially with accessor to its child,
  * for example: MyVariable or MyVariable.MyChild
  */
@@ -239,13 +239,14 @@ struct GD_CORE_API VariableAccessorOrVariableBracketAccessorNode : public Expres
 };
 
 /**
- * \brief A variable with bracket accessor or at least 2 "dot" accessors.
+ * \brief A variable, or object variable, with bracket accessor or at least 2 "dot" accessors.
+ *
+ * Example: `MyVariable["MyChildren"]` or `MyVariable.MyChildren.MyGrandChildren`.
+ * Example: `MyObject["MyVariable"]` or `MyObject.MyVariable.MyChildren`.
  *
- * Example: MyVariable[MyChildren] or MyVariable.MyChildren.MyGranChildren.
- * 
  * Other cases like "MyVariable" or "MyVariable.MyChildren" are IdentifierNode
  * to allow handling ambiguities.
- * 
+ *
  * \see gd::IdentifierNode
  * \see gd::VariableAccessorNode
  * \see gd::VariableBracketAccessorNode
@@ -267,7 +268,7 @@ struct GD_CORE_API VariableNode : public FunctionCallOrObjectFunctionNameOrEmpty
 };
 
 /**
- * \brief A bracket accessor of a variable. Example: MyChild
+ * \brief A direct accessor to a child variable. Example: MyChild
  * in MyVariable.MyChild
  */
 struct GD_CORE_API VariableAccessorNode
@@ -285,7 +286,7 @@ struct GD_CORE_API VariableAccessorNode
 };
 
 /**
- * \brief A bracket accessor of a variable. Example: ["MyChild"]
+ * \brief A bracket accessor to a child variable. Example: ["MyChild"]
  * (in MyVariable["MyChild"]).
  */
 struct GD_CORE_API VariableBracketAccessorNode
@@ -303,10 +304,10 @@ struct GD_CORE_API VariableBracketAccessorNode
 /**
  * \brief The name of a function to call on an object or the behavior
  * For example: "MyObject.Physics::LinearVelocity".
- * 
+ *
  * Other cases like "MyObject.Function" or "MyObject.Physics" are IdentifierNode
  * to allow handling ambiguities.
- * 
+ *
  * \see gd::IdentifierNode
  */
 struct GD_CORE_API ObjectFunctionNameNode

Core/GDCore/Events/Parsers/GrammarTerminals.h

@@ -75,10 +75,21 @@ inline bool IsZeroDigit(gd::String::value_type character) {
   return character == '0';
 }
 
+inline bool IsAdditionalReservedCharacter(gd::String::value_type character) {
+  // These characters are not part of the grammar - but are often used in programming language
+  // and could become operators or part of the grammar one day.
+  return character == '~' || character == '\'' || character == '%' ||
+         character == '#' || character == '@' || character == '|' ||
+         character == '&' || character == '`' || character == '$' ||
+         character == ';';
+
+}
+
 /**
  * Check if the given character can be used in an identifier. This is
  * any unicode character, except for:
- * `, . " () [] {} + - < > ? ^ = \ : ! / *` and whitespaces (space, line break, carriage return).
+ * `, . " () [] {} + - < > ? ^ = \ : ! / * ~ ' % # @ | & $ ;`
+ * and backtick and whitespaces (space, line break, carriage return).
  *
  * This is loosely based on what is allowed in languages like JavaScript
  * (see https://mathiasbynens.be/notes/javascript-properties), without support
@@ -96,7 +107,7 @@ inline bool IsAllowedInIdentifier(gd::String::value_type character) {
   if (!IsParameterSeparator(character) && !IsDot(character) &&
       !IsQuote(character) && !IsBracket(character) &&
       !IsExpressionOperator(character) && !IsTermOperator(character) &&
-      !IsWhitespace(character)) {
+      !IsWhitespace(character) && !IsAdditionalReservedCharacter(character)) {
     return true;
   }
 

Core/GDCore/Extensions/Builtin/AdvancedExtension.cpp

@@ -115,21 +115,23 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAdvancedExtension(
       .AddExpression(
           "GetArgumentAsNumber",
           _("Get function parameter value"),
-          _("Get function parameter (also called \"argument\") value."),
+          _("Get function parameter (also called \"argument\") value. You don't need this most of the time as you can simply write the parameter name in an expression."),
           "",
           "res/function16.png")
       .AddParameter("functionParameterName", _("Parameter name"), "number,string,boolean")
-      .SetRelevantForFunctionEventsOnly();
+      .SetRelevantForFunctionEventsOnly()
+      .SetHidden();
 
   extension
       .AddStrExpression(
           "GetArgumentAsString",
           _("Get function parameter text"),
-          _("Get function parameter (also called \"argument\") text."),
+          _("Get function parameter (also called \"argument\") text. You don't need this most of the time as you can simply write the parameter name in an expression."),
           "",
           "res/function16.png")
       .AddParameter("functionParameterName", _("Parameter name"), "number,string,boolean")
-      .SetRelevantForFunctionEventsOnly();
+      .SetRelevantForFunctionEventsOnly()
+      .SetHidden();
 
   extension
       .AddCondition(

Core/GDCore/Extensions/Builtin/AllBuiltinExtensions.h

@@ -49,6 +49,7 @@ class GD_CORE_API BuiltinExtensionsImplementer {
   static void ImplementsAnimatableExtension(gd::PlatformExtension& extension);
   static void ImplementsEffectExtension(gd::PlatformExtension& extension);
   static void ImplementsOpacityExtension(gd::PlatformExtension& extension);
+  static void ImplementsTextContainerExtension(gd::PlatformExtension& extension);
 };
 
 }  // namespace gd

Core/GDCore/Extensions/Builtin/BaseObjectExtension.cpp

@@ -617,6 +617,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
           "number", ParameterOptions::MakeNewOptions())
       .MarkAsAdvanced();
 
+  // Deprecated
   obj.AddCondition("AngleOfDisplacement",
                    _("Angle of movement (using forces)"),
                    _("Compare the angle of movement of an object according to "
@@ -626,7 +627,20 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
                    _("Movement using forces"),
                    "res/conditions/vitesse24.png",
                    "res/conditions/vitesse.png")
+      .SetHidden()
+      .AddParameter("object", _("Object"))
+      .AddParameter("expression", _("Angle, in degrees"))
+      .AddParameter("expression", _("Tolerance, in degrees"))
+      .MarkAsAdvanced();
 
+  obj.AddCondition("IsTotalForceAngleAround",
+                   _("Angle of movement (using forces)"),
+                   _("Compare the angle of movement of an object according to "
+                     "the forces applied on it."),
+                   _("Angle of movement of _PARAM0_ is _PARAM1_ ± _PARAM2_°"),
+                   _("Movement using forces"),
+                   "res/conditions/vitesse24.png",
+                   "res/conditions/vitesse.png")
       .AddParameter("object", _("Object"))
       .AddParameter("expression", _("Angle, in degrees"))
       .AddParameter("expression", _("Tolerance, in degrees"))
@@ -1277,9 +1291,9 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
 
   // Deprecated
   obj.AddAction("SetEffectDoubleParameter",
-                _("Effect parameter (number)"),
-                _("Change the value of a parameter of an effect.") + "\n" +
-                    _("You can find the parameter names (and change the effect "
+                _("Effect property (number)"),
+                _("Change the value of a property of an effect.") + "\n" +
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Set _PARAM2_ to _PARAM3_ for effect _PARAM1_ of _PARAM0_"),
                 _("Effects"),
@@ -1287,17 +1301,17 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
                 "res/actions/effect.png")
       .AddParameter("object", _("Object"))
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
       .AddParameter("expression", _("New value"))
       .MarkAsSimple()
       .SetHidden();
 
   // Deprecated
   obj.AddAction("SetEffectStringParameter",
-                _("Effect parameter (string)"),
-                _("Change the value (string) of a parameter of an effect.") +
+                _("Effect property (string)"),
+                _("Change the value (string) of a property of an effect.") +
                     "\n" +
-                    _("You can find the parameter names (and change the effect "
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Set _PARAM2_ to _PARAM3_ for effect _PARAM1_ of _PARAM0_"),
                 _("Effects"),
@@ -1305,16 +1319,16 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
                 "res/actions/effect.png")
       .AddParameter("object", _("Object"))
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
       .AddParameter("string", _("New value"))
       .MarkAsSimple()
       .SetHidden();
 
   // Deprecated
   obj.AddAction("SetEffectBooleanParameter",
-                _("Effect parameter (enable or disable)"),
-                _("Enable or disable a parameter of an effect.") + "\n" +
-                    _("You can find the parameter names (and change the effect "
+                _("Effect property (enable or disable)"),
+                _("Enable or disable a property of an effect.") + "\n" +
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Enable _PARAM2_ for effect _PARAM1_ of _PARAM0_: _PARAM3_"),
                 _("Effects"),
@@ -1322,8 +1336,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsBaseObjectExtension(
                 "res/actions/effect.png")
       .AddParameter("object", _("Object"))
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
-      .AddParameter("yesorno", _("Enable?"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
+      .AddParameter("yesorno", _("Enable this property"))
       .MarkAsSimple()
       .SetHidden();
 

Core/GDCore/Extensions/Builtin/CameraExtension.cpp

@@ -444,9 +444,9 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsCameraExtension(
   extension
       .AddAction(
           "SetLayerEffectParameter",
-          _("Effect parameter (number)"),
-          _("Change the value of a parameter of an effect.") + "\n" +
-              _("You can find the parameter names (and change the effect "
+          _("Effect property (number)"),
+          _("Change the value of a property of an effect.") + "\n" +
+              _("You can find the property names (and change the effect "
                 "names) in the effects window."),
           _("Set _PARAM3_ to _PARAM4_ for effect _PARAM2_ of layer _PARAM1_"),
           _("Effects"),
@@ -456,16 +456,16 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsCameraExtension(
       .AddParameter("layer", _("Layer"), "", true)
       .SetDefaultValue("\"\"")
       .AddParameter("layerEffectName", _("Effect name"))
-      .AddParameter("layerEffectParameterName", _("Parameter name"))
+      .AddParameter("layerEffectParameterName", _("Property name"))
       .AddParameter("expression", _("New value"))
       .MarkAsAdvanced();
 
   extension
       .AddAction(
           "SetLayerEffectStringParameter",
-          _("Effect parameter (string)"),
-          _("Change the value (string) of a parameter of an effect.") + "\n" +
-              _("You can find the parameter names (and change the effect "
+          _("Effect property (string)"),
+          _("Change the value (string) of a property of an effect.") + "\n" +
+              _("You can find the property names (and change the effect "
                 "names) in the effects window."),
           _("Set _PARAM3_ to _PARAM4_ for effect _PARAM2_ of layer _PARAM1_"),
           _("Effects"),
@@ -475,16 +475,16 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsCameraExtension(
       .AddParameter("layer", _("Layer"), "", true)
       .SetDefaultValue("\"\"")
       .AddParameter("layerEffectName", _("Effect name"))
-      .AddParameter("layerEffectParameterName", _("Parameter name"))
+      .AddParameter("layerEffectParameterName", _("Property name"))
       .AddParameter("string", _("New value"))
       .MarkAsAdvanced();
 
   extension
       .AddAction(
           "SetLayerEffectBooleanParameter",
-          _("Effect parameter (enable or disable)"),
-          _("Enable or disable a parameter of an effect.") + "\n" +
-              _("You can find the parameter names (and change the effect "
+          _("Effect property (enable or disable)"),
+          _("Enable or disable a property of an effect.") + "\n" +
+              _("You can find the property names (and change the effect "
                 "names) in the effects window."),
           _("Enable _PARAM3_ for effect _PARAM2_ of layer _PARAM1_: _PARAM4_"),
           _("Effects"),
@@ -494,8 +494,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsCameraExtension(
       .AddParameter("layer", _("Layer"), "", true)
       .SetDefaultValue("\"\"")
       .AddParameter("layerEffectName", _("Effect name"))
-      .AddParameter("layerEffectParameterName", _("Parameter name"))
-      .AddParameter("yesorno", _("Enable this parameter"))
+      .AddParameter("layerEffectParameterName", _("Property name"))
+      .AddParameter("yesorno", _("Enable this property"))
       .MarkAsAdvanced();
 
   extension

Core/GDCore/Extensions/Builtin/Capabilities/AnimatableExtension.cpp

@@ -23,6 +23,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
                                "Florian Rival",
                                "Open source (MIT License)")
       .SetExtensionHelpPath("/objects");
+  extension.AddInstructionOrExpressionGroupMetadata(_("Animatable capability"))
+      .SetIcon("res/actions/animation24.png");
   extension.AddInstructionOrExpressionGroupMetadata(_("Animations and images"))
       .SetIcon("res/actions/animation24.png");
 
@@ -53,13 +55,14 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
           "number", gd::ParameterOptions::MakeNewOptions().SetDescription(
                         _("Animation index")))
       .MarkAsSimple();
+  aut.GetAllExpressions()["Index"].SetGroup("");
 
   aut.AddExpressionAndConditionAndAction(
          "string",
          "Name",
          _("Animation (by name)"),
          _("the animation played by the object using the name of the "
-           "animation."),
+           "animation"),
          _("the animation"),
          _("Animations and images"),
          "res/actions/animation24.png")
@@ -69,10 +72,11 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
           "objectAnimationName", gd::ParameterOptions::MakeNewOptions().SetDescription(
                         _("Animation name")))
       .MarkAsSimple();
+  aut.GetAllStrExpressions()["Name"].SetGroup("");
 
   aut.AddScopedAction("PauseAnimation",
                 _("Pause the animation"),
-                _("Pause the animation of the object"),
+                _("Pause the animation of the object."),
                 _("Pause the animation of _PARAM0_"),
                 _("Animations and images"),
                 "res/actions/animation24.png",
@@ -83,7 +87,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
 
   aut.AddScopedAction("PlayAnimation",
                 _("Resume the animation"),
-                _("Resume the animation of the object"),
+                _("Resume the animation of the object."),
                 _("Resume the animation of _PARAM0_"),
                 _("Animations and images"),
                 "res/actions/animation24.png",
@@ -107,6 +111,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
           "number", gd::ParameterOptions::MakeNewOptions().SetDescription(
                         _("Speed scale")))
       .MarkAsSimple();
+  aut.GetAllExpressions()["SpeedScale"].SetGroup("");
 
   aut.AddScopedCondition("IsAnimationPaused",
                    _("Animation paused"),
@@ -130,6 +135,31 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsAnimatableExtension(
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "AnimatableBehavior")
       .MarkAsSimple();
+
+  aut.AddExpressionAndConditionAndAction(
+         "number",
+         "ElapsedTime",
+         _("Animation elapsed time"),
+         _("the elapsed time from the beginning of the animation (in seconds)"),
+         _("the animation elapsed time"),
+         _("Animations and images"),
+         "res/actions/animation24.png")
+      .AddParameter("object", _("Object"))
+      .AddParameter("behavior", _("Behavior"), "AnimatableBehavior")
+      .UseStandardParameters(
+          "number", gd::ParameterOptions::MakeNewOptions().SetDescription(
+                        _("Elapsed time (in seconds)")))
+      .MarkAsAdvanced();
+  aut.GetAllExpressions()["ElapsedTime"].SetGroup("");
+
+  aut.AddExpression(
+         "Duration",
+         _("Animation duration"),
+         _("Return the current animation duration (in seconds)."),
+         _("Animations and images"),
+         "res/actions/animation24.png")
+      .AddParameter("object", _("Object"))
+      .AddParameter("behavior", _("Behavior"), "AnimatableBehavior");
 }
 
 }  // namespace gd

Core/GDCore/Extensions/Builtin/Capabilities/EffectExtension.cpp

@@ -52,9 +52,9 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsEffectExtension(
       .MarkAsSimple();
 
   aut.AddScopedAction("SetEffectDoubleParameter",
-                _("Effect parameter (number)"),
-                _("Change the value of a parameter of an effect.") + "\n" +
-                    _("You can find the parameter names (and change the effect "
+                _("Effect property (number)"),
+                _("Change the value of a property of an effect.") + "\n" +
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Set _PARAM3_ to _PARAM4_ for effect _PARAM2_ of _PARAM0_"),
                 _("Effects"),
@@ -63,15 +63,15 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsEffectExtension(
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "EffectBehavior")
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
       .AddParameter("expression", _("New value"))
       .MarkAsSimple();
 
   aut.AddScopedAction("SetEffectStringParameter",
-                _("Effect parameter (string)"),
-                _("Change the value (string) of a parameter of an effect.") +
+                _("Effect property (string)"),
+                _("Change the value (string) of a property of an effect.") +
                     "\n" +
-                    _("You can find the parameter names (and change the effect "
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Set _PARAM3_ to _PARAM4_ for effect _PARAM2_ of _PARAM0_"),
                 _("Effects"),
@@ -80,14 +80,14 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsEffectExtension(
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "EffectBehavior")
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
       .AddParameter("string", _("New value"))
       .MarkAsSimple();
 
   aut.AddScopedAction("SetEffectBooleanParameter",
-                _("Effect parameter (enable or disable)"),
-                _("Enable or disable a parameter of an effect.") + "\n" +
-                    _("You can find the parameter names (and change the effect "
+                _("Effect property (enable or disable)"),
+                _("Enable or disable a property of an effect.") + "\n" +
+                    _("You can find the property names (and change the effect "
                       "names) in the effects window."),
                 _("Enable _PARAM3_ for effect _PARAM2_ of _PARAM0_: _PARAM4_"),
                 _("Effects"),
@@ -96,8 +96,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsEffectExtension(
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "EffectBehavior")
       .AddParameter("objectEffectName", _("Effect name"))
-      .AddParameter("objectEffectParameterName", _("Parameter name"))
-      .AddParameter("yesorno", _("Enable?"))
+      .AddParameter("objectEffectParameterName", _("Property name"))
+      .AddParameter("yesorno", _("Enable this property"))
       .MarkAsSimple();
 
   aut.AddScopedCondition("IsEffectEnabled",

Core/GDCore/Extensions/Builtin/Capabilities/OpacityExtension.cpp

@@ -23,6 +23,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsOpacityExtension(
                                "Florian Rival",
                                "Open source (MIT License)")
       .SetExtensionHelpPath("/objects");
+  extension.AddInstructionOrExpressionGroupMetadata(_("Opacity capability"))
+      .SetIcon("res/actions/opacity24.png");
   extension.AddInstructionOrExpressionGroupMetadata(_("Visibility"))
       .SetIcon("res/actions/opacity24.png");
 
@@ -54,6 +56,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsOpacityExtension(
                         _("Opacity (0-255)")))
       .SetFunctionName("setOpacity")
       .SetGetter("getOpacity");
+  aut.GetAllExpressions()["Value"].SetGroup("");
 }
 
 }  // namespace gd

Core/GDCore/Extensions/Builtin/Capabilities/ResizableExtension.cpp

@@ -14,7 +14,7 @@ using namespace std;
 namespace gd {
 
 void GD_CORE_API BuiltinExtensionsImplementer::ImplementsResizableExtension(
-    gd::PlatformExtension& extension) {
+    gd::PlatformExtension &extension) {
   extension
       .SetExtensionInformation("ResizableCapability",
                                _("Resizable capability"),
@@ -22,84 +22,86 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsResizableExtension(
                                "Florian Rival",
                                "Open source (MIT License)")
       .SetExtensionHelpPath("/objects");
-  extension.AddInstructionOrExpressionGroupMetadata(_("Size"))
-      .SetIcon("res/actions/scale24_black.png");
+  extension.AddInstructionOrExpressionGroupMetadata(_("Size")).SetIcon(
+      "res/actions/scale24_black.png");
 
-  gd::BehaviorMetadata& aut = extension.AddBehavior(
-      "ResizableBehavior",
-      _("Resizable capability"),
-      "Resizable",
-      _("Change the object dimensions."),
-      "",
-      "res/actions/scale24_black.png",
-      "ResizableBehavior",
-      std::make_shared<gd::Behavior>(),
-      std::make_shared<gd::BehaviorsSharedData>())
-    .SetHidden();
+  gd::BehaviorMetadata &aut =
+      extension
+          .AddBehavior("ResizableBehavior",
+                       _("Resizable capability"),
+                       "Resizable",
+                       _("Change the object dimensions."),
+                       "",
+                       "res/actions/scale24_black.png",
+                       "ResizableBehavior",
+                       std::make_shared<gd::Behavior>(),
+                       std::make_shared<gd::BehaviorsSharedData>())
+          .SetHidden();
 
   aut.AddScopedAction("SetWidth",
-                _("Width"),
-                _("Change the width of the object."),
-                _("the width"),
-                _("Size"),
-                "res/actions/scaleWidth24_black.png",
-                "res/actions/scaleWidth_black.png")
+                      _("Width"),
+                      _("Change the width of the object."),
+                      _("the width"),
+                      _("Size"),
+                      "res/actions/scaleWidth24_black.png",
+                      "res/actions/scaleWidth_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ResizableBehavior")
-      .UseStandardOperatorParameters("number",
-                                     ParameterOptions::MakeNewOptions().SetDescription(
-                                        _("Width")))
+      .UseStandardOperatorParameters(
+          "number",
+          ParameterOptions::MakeNewOptions().SetDescription(_("Width")))
       .MarkAsAdvanced();
 
   aut.AddScopedCondition("Width",
-                   _("Width"),
-                   _("Compare the width of the object."),
-                   _("the width"),
-                   _("Size"),
-                   "res/conditions/scaleWidth24_black.png",
-                   "res/conditions/scaleWidth_black.png")
+                         _("Width"),
+                         _("Compare the width of the object."),
+                         _("the width"),
+                         _("Size"),
+                         "res/conditions/scaleWidth24_black.png",
+                         "res/conditions/scaleWidth_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ResizableBehavior")
       .UseStandardRelationalOperatorParameters(
-          "number", ParameterOptions::MakeNewOptions().SetDescription(
-                        _("Width")))
+          "number",
+          ParameterOptions::MakeNewOptions().SetDescription(_("Width")))
       .MarkAsAdvanced();
 
   aut.AddScopedAction("SetHeight",
-                _("Height"),
-                _("Change the height of the object."),
-                _("the height"),
-                _("Size"),
-                "res/actions/scaleHeight24_black.png",
-                "res/actions/scaleHeight_black.png")
+                      _("Height"),
+                      _("Change the height of the object."),
+                      _("the height"),
+                      _("Size"),
+                      "res/actions/scaleHeight24_black.png",
+                      "res/actions/scaleHeight_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ResizableBehavior")
-      .UseStandardOperatorParameters("number",
-                                     ParameterOptions::MakeNewOptions().SetDescription(
-                                        _("Height")))
+      .UseStandardOperatorParameters(
+          "number",
+          ParameterOptions::MakeNewOptions().SetDescription(_("Height")))
       .MarkAsAdvanced();
 
   aut.AddScopedCondition("Height",
-                   _("Height"),
-                   _("Compare the height of the object."),
-                   _("the height"),
-                   _("Size"),
-                   "res/conditions/scaleHeight24_black.png",
-                   "res/conditions/scaleHeight_black.png")
+                         _("Height"),
+                         _("Compare the height of the object."),
+                         _("the height"),
+                         _("Size"),
+                         "res/conditions/scaleHeight24_black.png",
+                         "res/conditions/scaleHeight_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ResizableBehavior")
       .UseStandardRelationalOperatorParameters(
-          "number", ParameterOptions::MakeNewOptions().SetDescription(
-                        _("Height")))
+          "number",
+          ParameterOptions::MakeNewOptions().SetDescription(_("Height")))
       .MarkAsAdvanced();
 
-  aut.AddScopedAction("SetSize",
-                _("Size"),
-                _("Change the size of an object."),
-                _("Change the size of _PARAM0_: set to _PARAM1_ x _PARAM2_"),
-                _("Size"),
-                "res/actions/scale24_black.png",
-                "res/actions/scale_black.png")
+  aut.AddScopedAction(
+         "SetSize",
+         _("Size"),
+         _("Change the size of an object."),
+         _("Change the size of _PARAM0_: set to _PARAM2_ x _PARAM3_"),
+         _("Size"),
+         "res/actions/scale24_black.png",
+         "res/actions/scale_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ResizableBehavior")
       .AddParameter("expression", _("Width"))

Core/GDCore/Extensions/Builtin/Capabilities/ScalableExtension.cpp

@@ -23,6 +23,8 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
                                "Florian Rival",
                                "Open source (MIT License)")
       .SetExtensionHelpPath("/objects");
+  extension.AddInstructionOrExpressionGroupMetadata(_("Scalable capability"))
+      .SetIcon("res/actions/scale24_black.png");
   extension.AddInstructionOrExpressionGroupMetadata(_("Size"))
       .SetIcon("res/actions/scale24_black.png");
 
@@ -53,6 +55,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
           gd::ParameterOptions::MakeNewOptions().SetDescription(
               _("Scale (1 by default)")))
       .MarkAsAdvanced();
+  aut.GetAllExpressions()["Value"].SetGroup("");
 
   aut.AddExpressionAndConditionAndAction(
          "number",
@@ -61,7 +64,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
          _("the scale on X axis of the object (default scale is 1)"),
          _("the scale on X axis"),
          _("Scale"),
-         "res/actions/scale24_black.png")
+         "res/actions/scaleWidth24_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ScalableBehavior")
       .UseStandardParameters(
@@ -69,6 +72,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
           gd::ParameterOptions::MakeNewOptions().SetDescription(
               _("Scale (1 by default)")))
       .MarkAsAdvanced();
+  aut.GetAllExpressions()["X"].SetGroup("");
 
   aut.AddExpressionAndConditionAndAction(
          "number",
@@ -77,7 +81,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
          _("the scale on Y axis of the object (default scale is 1)"),
          _("the scale on Y axis"),
          _("Scale"),
-         "res/actions/scale24_black.png")
+         "res/actions/scaleHeight24_black.png")
       .AddParameter("object", _("Object"))
       .AddParameter("behavior", _("Behavior"), "ScalableBehavior")
       .UseStandardParameters(
@@ -85,6 +89,7 @@ void GD_CORE_API BuiltinExtensionsImplementer::ImplementsScalableExtension(
           gd::ParameterOptions::MakeNewOptions().SetDescription(
               _("Scale (1 by default)")))
       .MarkAsAdvanced();
+  aut.GetAllExpressions()["Y"].SetGroup("");
 }
 
 }  // namespace gd

Core/GDCore/Extensions/Builtin/Capabilities/TextContainerExtension.cpp

@@ -0,0 +1,58 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the GNU Lesser General Public
+ * License.
+ */
+#include "GDCore/Extensions/Builtin/AllBuiltinExtensions.h"
+#include "GDCore/Extensions/Metadata/MultipleInstructionMetadata.h"
+#include "GDCore/Project/Behavior.h"
+#include "GDCore/Project/BehaviorsSharedData.h"
+#include "GDCore/Project/Object.h"
+#include "GDCore/Tools/Localization.h"
+
+using namespace std;
+namespace gd {
+
+void GD_CORE_API BuiltinExtensionsImplementer::ImplementsTextContainerExtension(
+    gd::PlatformExtension& extension) {
+  extension
+      .SetExtensionInformation("TextContainerCapability",
+                               _("Text capability"),
+                               _("Animate objects."),
+                               "Florian Rival",
+                               "Open source (MIT License)")
+      .SetExtensionHelpPath("/objects");
+  extension.AddInstructionOrExpressionGroupMetadata(_("Text capability"))
+      .SetIcon("res/conditions/text24_black.png");
+
+  gd::BehaviorMetadata& aut = extension.AddBehavior(
+      "TextContainerBehavior",
+      _("Text capability"),
+      "Text",
+      _("Access objects text."),
+      "",
+      "res/conditions/text24_black.png",
+      "TextContainerBehavior",
+      std::make_shared<gd::Behavior>(),
+      std::make_shared<gd::BehaviorsSharedData>())
+    .SetHidden();
+
+  aut.AddExpressionAndConditionAndAction(
+         "string",
+         "Value",
+         _("Text"),
+         _("the text"),
+         _("the text"),
+         "",
+         "res/conditions/text24_black.png")
+      .AddParameter("object", _("Object"))
+      .AddParameter("behavior", _("Behavior"), "TextContainerBehavior")
+      .UseStandardParameters(
+          "string", gd::ParameterOptions::MakeNewOptions().SetDescription(
+                        _("Text")))
+      .MarkAsSimple();
+  aut.GetAllStrExpressions()["Value"].SetGroup("");
+}
+
+}  // namespace gd

Core/GDCore/Extensions/Builtin/CommonInstructionsExtension.cpp

@@ -35,6 +35,8 @@ BuiltinExtensionsImplementer::ImplementsCommonInstructionsExtension(
       .AddInstructionOrExpressionGroupMetadata(_("Events and control flow"))
       .SetIcon("res/conditions/toujours24_black.png");
 
+  // This condition is deprecated as this does not bring anything new
+  // and can be confusing or misleading for beginners.
   extension
       .AddCondition("Always",
                     _("Always"),
@@ -46,7 +48,8 @@ BuiltinExtensionsImplementer::ImplementsCommonInstructionsExtension(
                     "res/conditions/toujours_black.png")
       .SetHelpPath("/all-features/advanced-conditions")
       .AddCodeOnlyParameter("conditionInverted", "")
-      .MarkAsAdvanced();
+      .MarkAsAdvanced()
+      .SetHidden();
 
   // Compatibility with GD <= 5.0.127
   extension
@@ -114,8 +117,9 @@ BuiltinExtensionsImplementer::ImplementsCommonInstructionsExtension(
 
   // Compatibility with GD <= 5.0.127
   extension
-      .AddDuplicatedCondition(
-          "Egal", "BuiltinCommonInstructions::CompareNumbers", {.unscoped = true})
+      .AddDuplicatedCondition("Egal",
+                              "BuiltinCommonInstructions::CompareNumbers",
+                              {.unscoped = true})
       .SetHidden();
   // end of compatibility code
 
@@ -135,8 +139,9 @@ BuiltinExtensionsImplementer::ImplementsCommonInstructionsExtension(
 
   // Compatibility with GD <= 5.0.127
   extension
-      .AddDuplicatedCondition(
-          "StrEqual", "BuiltinCommonInstructions::CompareStrings", {.unscoped = true})
+      .AddDuplicatedCondition("StrEqual",
+                              "BuiltinCommonInstructions::CompareStrings",
+                              {.unscoped = true})
       .SetHidden();
   // end of compatibility code
 

Core/GDCore/Extensions/Builtin/ExternalLayoutsExtension.cpp

@@ -38,6 +38,8 @@ BuiltinExtensionsImplementer::ImplementsExternalLayoutsExtension(
       .SetDefaultValue("0")
       .AddParameter("expression", _("Y position of the origin"), "", true)
       .SetDefaultValue("0")
+      .AddParameter("expression", _("Z position of the origin"), "", true)
+      .SetDefaultValue("0")
       .MarkAsAdvanced();
 }
 

Core/GDCore/Extensions/Metadata/MetadataProvider.cpp

@@ -14,6 +14,7 @@
 #include "GDCore/Extensions/Platform.h"
 #include "GDCore/Extensions/PlatformExtension.h"
 #include "GDCore/Project/Layout.h"  // For GetTypeOfObject and GetTypeOfBehavior
+#include "GDCore/Project/ObjectsContainersList.h"
 #include "GDCore/String.h"
 #include "GDCore/Events/Parsers/ExpressionParser2.h"
 
@@ -391,20 +392,19 @@ MetadataProvider::GetBehaviorAnyExpressionMetadata(const gd::Platform& platform,
 }
 
 const gd::ExpressionMetadata& MetadataProvider::GetFunctionCallMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& node) {
 
   if (!node.behaviorName.empty()) {
-    gd::String behaviorType = 
-        GetTypeOfBehavior(globalObjectsContainer, objectsContainer, node.behaviorName);
+    gd::String behaviorType =
+        objectsContainersList.GetTypeOfBehavior(node.behaviorName);
     return MetadataProvider::GetBehaviorAnyExpressionMetadata(
             platform, behaviorType, node.functionName);
   }
   else if (!node.objectName.empty()) {
-    gd::String objectType = 
-        GetTypeOfObject(globalObjectsContainer, objectsContainer, node.objectName);
+    gd::String objectType =
+        objectsContainersList.GetTypeOfObject(node.objectName);
     return MetadataProvider::GetObjectAnyExpressionMetadata(
                   platform, objectType, node.functionName);
   }
@@ -412,10 +412,9 @@ const gd::ExpressionMetadata& MetadataProvider::GetFunctionCallMetadata(
   return MetadataProvider::GetAnyExpressionMetadata(platform, node.functionName);
 }
 
-  const gd::ParameterMetadata* MetadataProvider::GetFunctionCallParameterMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+const gd::ParameterMetadata* MetadataProvider::GetFunctionCallParameterMetadata(
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& functionCall,
     ExpressionNode& parameter) {
       int parameterIndex = -1;
@@ -429,17 +428,15 @@ const gd::ExpressionMetadata& MetadataProvider::GetFunctionCallMetadata(
         return nullptr;
       }
       return MetadataProvider::GetFunctionCallParameterMetadata(
-          platform, 
-          globalObjectsContainer,
-          objectsContainer,
+          platform,
+          objectsContainersList,
           functionCall,
           parameterIndex);
 }
 
-  const gd::ParameterMetadata* MetadataProvider::GetFunctionCallParameterMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+const gd::ParameterMetadata* MetadataProvider::GetFunctionCallParameterMetadata(
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& functionCall,
     int parameterIndex) {
       // Search the parameter metadata index skipping invisible ones.
@@ -448,7 +445,7 @@ const gd::ExpressionMetadata& MetadataProvider::GetFunctionCallMetadata(
           ExpressionParser2::WrittenParametersFirstIndex(
               functionCall.objectName, functionCall.behaviorName);
       const gd::ExpressionMetadata &metadata = MetadataProvider::GetFunctionCallMetadata(
-          platform, globalObjectsContainer, objectsContainer, functionCall);
+          platform, objectsContainersList, functionCall);
 
       if (IsBadExpressionMetadata(metadata)) {
         return nullptr;

Core/GDCore/Extensions/Metadata/MetadataProvider.h

@@ -15,6 +15,7 @@ class ExpressionMetadata;
 class ExpressionMetadata;
 class Platform;
 class PlatformExtension;
+class ObjectsContainersList;
 struct FunctionCallNode;
 struct ExpressionNode;
 }  // namespace gd
@@ -237,22 +238,19 @@ class GD_CORE_API MetadataProvider {
       const gd::Platform& platform, gd::String objectType, gd::String exprType);
 
   static const gd::ExpressionMetadata& GetFunctionCallMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& node);
 
   static const gd::ParameterMetadata* GetFunctionCallParameterMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& functionCall,
     ExpressionNode& parameter);
 
   static const gd::ParameterMetadata* GetFunctionCallParameterMetadata(
-    const gd::Platform& platform, 
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer,
+    const gd::Platform& platform,
+    const gd::ObjectsContainersList &objectsContainersList,
     FunctionCallNode& functionCall,
     int parameterIndex);
 

Core/GDCore/Extensions/Metadata/ParameterMetadata.h

@@ -34,6 +34,11 @@ class GD_CORE_API ParameterMetadata {
    */
   gd::ValueTypeMetadata &GetValueTypeMetadata() { return valueTypeMetadata; }
 
+  /**
+   * \brief Return the metadata of the parameter type.
+   */
+  const gd::ValueTypeMetadata &GetValueTypeMetadata() const { return valueTypeMetadata; }
+
   /**
    * \brief Set the metadata of the parameter type.
    */

Core/GDCore/Extensions/Metadata/ParameterMetadataTools.cpp

@@ -8,6 +8,7 @@
 #include "GDCore/Events/Expression.h"
 #include "GDCore/Project/Object.h"
 #include "GDCore/Project/ObjectsContainer.h"
+#include "GDCore/Project/ObjectsContainersList.h"
 #include "GDCore/Project/Project.h"
 #include "GDCore/String.h"
 #include "InstructionMetadata.h"
@@ -15,6 +16,8 @@
 #include "GDCore/Events/Parsers/ExpressionParser2NodePrinter.h"
 
 namespace gd {
+const ParameterMetadata ParameterMetadataTools::badParameterMetadata;
+
 void ParameterMetadataTools::ParametersToObjectsContainer(
     const gd::Project& project,
     const std::vector<gd::ParameterMetadata>& parameters,
@@ -57,6 +60,55 @@ void ParameterMetadataTools::ParametersToObjectsContainer(
   }
 }
 
+void ParameterMetadataTools::ForEachParameterMatchingSearch(
+    const std::vector<const std::vector<gd::ParameterMetadata>*>&
+        parametersVectorsList,
+    const gd::String& search,
+    std::function<void(const gd::ParameterMetadata&)> cb) {
+  for (auto it = parametersVectorsList.rbegin();
+       it != parametersVectorsList.rend();
+       ++it) {
+    const std::vector<gd::ParameterMetadata>* parametersVector = *it;
+
+    for (const auto& parameterMetadata: *parametersVector) {
+      if (parameterMetadata.GetName().FindCaseInsensitive(search) != gd::String::npos) cb(parameterMetadata);
+    }
+  }
+}
+
+bool ParameterMetadataTools::Has(
+      const std::vector<const std::vector<gd::ParameterMetadata>*>& parametersVectorsList,
+      const gd::String& parameterName) {
+  for (auto it = parametersVectorsList.rbegin();
+       it != parametersVectorsList.rend();
+       ++it) {
+    const std::vector<gd::ParameterMetadata>* parametersVector = *it;
+
+    for (const auto& parameterMetadata: *parametersVector) {
+      if (parameterMetadata.GetName() == parameterName) return true;
+    }
+  }
+
+  return false;
+}
+
+const gd::ParameterMetadata& ParameterMetadataTools::Get(
+    const std::vector<const std::vector<gd::ParameterMetadata>*>&
+        parametersVectorsList,
+    const gd::String& parameterName) {
+  for (auto it = parametersVectorsList.rbegin();
+       it != parametersVectorsList.rend();
+       ++it) {
+    const std::vector<gd::ParameterMetadata>* parametersVector = *it;
+
+    for (const auto& parameterMetadata: *parametersVector) {
+      if (parameterMetadata.GetName() == parameterName) return parameterMetadata;
+    }
+  }
+
+  return badParameterMetadata;
+}
+
 void ParameterMetadataTools::IterateOverParameters(
     const std::vector<gd::Expression>& parameters,
     const std::vector<gd::ParameterMetadata>& parametersMetadata,
@@ -105,8 +157,7 @@ void ParameterMetadataTools::IterateOverParametersWithIndex(
 
 void ParameterMetadataTools::IterateOverParametersWithIndex(
     const gd::Platform &platform,
-    const gd::ObjectsContainer &globalObjectsContainer,
-    const gd::ObjectsContainer &objectsContainer, FunctionCallNode &node,
+    const gd::ObjectsContainersList &objectsContainersList, FunctionCallNode &node,
     std::function<void(const gd::ParameterMetadata &parameterMetadata,
                        std::unique_ptr<gd::ExpressionNode> &parameterNode,
                        size_t parameterIndex, const gd::String &lastObjectName)>
@@ -117,8 +168,7 @@ void ParameterMetadataTools::IterateOverParametersWithIndex(
   const gd::ExpressionMetadata &metadata =
       isObjectFunction ? MetadataProvider::GetObjectAnyExpressionMetadata(
                              platform,
-                             GetTypeOfObject(globalObjectsContainer,
-                                             objectsContainer, node.objectName),
+                             objectsContainersList.GetTypeOfObject(node.objectName),
                              node.functionName)
                        : MetadataProvider::GetAnyExpressionMetadata(
                              platform, node.functionName);

Core/GDCore/Extensions/Metadata/ParameterMetadataTools.h

@@ -3,9 +3,8 @@
  * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
  * reserved. This project is released under the MIT License.
  */
-#if defined(GD_IDE_ONLY)
-#ifndef ParameterMetadataTools_H
-#define ParameterMetadataTools_H
+#pragma once
+#include <functional>
 #include <vector>
 #include <memory>
 #include "GDCore/String.h"
@@ -13,6 +12,7 @@ namespace gd {
 class Platform;
 class Project;
 class ObjectsContainer;
+class ObjectsContainersList;
 class ParameterMetadata;
 class Expression;
 struct FunctionCallNode;
@@ -27,6 +27,19 @@ class GD_CORE_API ParameterMetadataTools {
       const std::vector<gd::ParameterMetadata>& parameters,
       gd::ObjectsContainer& outputObjectsContainer);
 
+  static void ForEachParameterMatchingSearch(
+      const std::vector<const std::vector<gd::ParameterMetadata>*>& parametersVectorsList,
+      const gd::String& search,
+      std::function<void(const gd::ParameterMetadata&)> cb);
+
+  static bool Has(
+      const std::vector<const std::vector<gd::ParameterMetadata>*>& parametersVectorsList,
+      const gd::String& parameterName);
+
+  static const gd::ParameterMetadata& Get(
+      const std::vector<const std::vector<gd::ParameterMetadata>*>& parametersVectorsList,
+      const gd::String& parameterName);
+
   /**
    * Iterate over a list of parameters and their values.
    * Callback function is called with the parameter metadata, its value
@@ -59,8 +72,7 @@ class GD_CORE_API ParameterMetadataTools {
    */
   static void IterateOverParametersWithIndex(
       const gd::Platform &platform,
-      const gd::ObjectsContainer &globalObjectsContainer,
-      const gd::ObjectsContainer &objectsContainer, FunctionCallNode &node,
+      const gd::ObjectsContainersList &objectsContainersList, FunctionCallNode &node,
       std::function<void(const gd::ParameterMetadata &parameterMetadata,
                          std::unique_ptr<gd::ExpressionNode> &parameterNode,
                          size_t parameterIndex,
@@ -74,8 +86,8 @@ class GD_CORE_API ParameterMetadataTools {
   static size_t GetObjectParameterIndexFor(
       const std::vector<gd::ParameterMetadata>& parametersMetadata,
       size_t parameterIndex);
+
+private:
+  static const gd::ParameterMetadata badParameterMetadata;
 };
 }  // namespace gd
-
-#endif  // ParameterMetadataTools_H
-#endif

Core/GDCore/Extensions/Metadata/ValueTypeMetadata.h

@@ -121,6 +121,13 @@ class GD_CORE_API ValueTypeMetadata {
     return gd::ValueTypeMetadata::IsTypeExpression("string", name);
   }
 
+  /**
+   * \brief Return true if the type is a boolean.
+   */
+  bool IsBoolean() const {
+    return gd::ValueTypeMetadata::IsTypeExpression("boolean", name);
+  }
+
   /**
    * \brief Return true if the type of the parameter is a number.
    * \note If you had a new type of parameter, also add it in the IDE (
@@ -131,6 +138,24 @@ class GD_CORE_API ValueTypeMetadata {
     return gd::ValueTypeMetadata::IsTypeExpression("variable", name);
   }
 
+  /**
+   * \brief Return true if the type is a variable but from a specific scope
+   * (scene, project or object). In new code, prefer to use the more generic "variable"
+   * parameter (which accepts any variable coming from an object or from containers in the scope).
+   */
+  bool IsLegacyPreScopedVariable() const {
+    return gd::ValueTypeMetadata::IsTypeLegacyPreScopedVariable(name);
+  }
+
+  /**
+   * \brief Return true if the type is a variable but from a specific scope
+   * (scene, project or object). In new code, prefer to use the more generic "variable"
+   * parameter (which accepts any variable coming from an object or from containers in the scope).
+   */
+  static bool IsTypeLegacyPreScopedVariable(const gd::String &type) {
+    return type == "scenevar" || type == "globalvar" || type == "objectvar";
+  }
+
   /**
    * \brief Return true if the type is representing one object
    * (or more, i.e: an object group).
@@ -175,8 +200,13 @@ class GD_CORE_API ValueTypeMetadata {
              parameterType == "externalLayoutName" ||
              parameterType == "leaderboardId" ||
              parameterType == "identifier";
+    } else if (type == "boolean") {
+      return parameterType == "yesorno" || parameterType == "trueorfalse";
     } else if (type == "variable") {
-      return parameterType == "objectvar" || parameterType == "globalvar" ||
+      return
+             parameterType == "variable" || // Any variable.
+             // Old, "pre-scoped" variables:
+             parameterType == "objectvar" || parameterType == "globalvar" ||
              parameterType == "scenevar";
     } else if (type == "resource") {
       return parameterType == "fontResource" ||
@@ -196,7 +226,7 @@ class GD_CORE_API ValueTypeMetadata {
    * \brief Return the expression type from the parameter type.
    * Declinations of "number" and "string" types (like "forceMultiplier" or
    * "sceneName") are replaced by "number" and "string".
-   * 
+   *
    * \note It only maps string and number types.
    */
   static const gd::String &GetExpressionPrimitiveValueType(const gd::String &parameterType);
@@ -205,7 +235,7 @@ class GD_CORE_API ValueTypeMetadata {
    * \brief Return the primitive type from the parameter type.
    * Declinations of "number" and "string" types (like "forceMultiplier" or
    * "sceneName") are replaced by "number" and "string".
-   * 
+   *
    * \note It also maps variable and boolean types.
    */
   static const gd::String &GetPrimitiveValueType(const gd::String &parameterType);

Core/GDCore/IDE/Events/ArbitraryEventsWorker.cpp

@@ -11,6 +11,8 @@
 #include "GDCore/Events/Event.h"
 #include "GDCore/Events/EventsList.h"
 #include "GDCore/Events/Instruction.h"
+#include "GDCore/Events/Expression.h"
+#include "GDCore/Extensions/Metadata/ParameterMetadata.h"
 #include "GDCore/String.h"
 
 using namespace std;
@@ -47,7 +49,14 @@ bool ArbitraryEventsWorker::VisitEvent(gd::BaseEvent& event) {
   for (std::size_t j = 0; j < actionsVectors.size(); ++j)
     VisitInstructionList(*actionsVectors[j], false);
 
-  return false;
+  auto allExpressionsWithMetadata = event.GetAllExpressionsWithMetadata();
+  for (auto& expressionAndMetadata : allExpressionsWithMetadata) {
+    shouldDelete |= VisitEventExpression(
+      *expressionAndMetadata.first, expressionAndMetadata.second);
+  }
+
+
+  return shouldDelete;
 }
 
 bool ArbitraryEventsWorker::VisitLinkEvent(gd::LinkEvent& linkEvent) {
@@ -75,6 +84,11 @@ bool ArbitraryEventsWorker::VisitInstruction(gd::Instruction& instruction,
   return DoVisitInstruction(instruction, isCondition);
 }
 
+bool ArbitraryEventsWorker::VisitEventExpression(gd::Expression& expression,
+                                                 const gd::ParameterMetadata& metadata) {
+  return DoVisitEventExpression(expression, metadata);
+}
+
 ArbitraryEventsWorkerWithContext::~ArbitraryEventsWorkerWithContext() {}
 
 
@@ -141,6 +155,12 @@ void ReadOnlyArbitraryEventsWorker::VisitInstruction(const gd::Instruction& inst
   DoVisitInstruction(instruction, isCondition);
 }
 
+
+void ReadOnlyArbitraryEventsWorker::VisitEventExpression(const gd::Expression& expression,
+                                                 const gd::ParameterMetadata& metadata) {
+  DoVisitEventExpression(expression, metadata);
+}
+
 void ReadOnlyArbitraryEventsWorker::StopAnyEventIteration() {
   shouldStopIteration = true;
 }

Core/GDCore/IDE/Events/ArbitraryEventsWorker.h

@@ -10,6 +10,7 @@
 #include <vector>
 #include "GDCore/Events/InstructionsList.h"
 #include "GDCore/Events/EventVisitor.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/String.h"
 namespace gd {
 class Instruction;
@@ -17,6 +18,8 @@ class BaseEvent;
 class LinkEvent;
 class EventsList;
 class ObjectsContainer;
+class Expression;
+class ParameterMetadata;
 }  // namespace gd
 
 namespace gd {
@@ -47,6 +50,7 @@ class GD_CORE_API ArbitraryEventsWorker : private EventVisitor {
   void VisitInstructionList(gd::InstructionsList& instructions,
                             bool areConditions);
   bool VisitInstruction(gd::Instruction& instruction, bool isCondition);
+  bool VisitEventExpression(gd::Expression& expression, const gd::ParameterMetadata& metadata);
 
   /**
    * Called to do some work on an event list.
@@ -62,9 +66,9 @@ class GD_CORE_API ArbitraryEventsWorker : private EventVisitor {
 
   /**
    * Called to do some work on a link event.
-   * 
+   *
    * Note that DoVisitEvent is also called with this event.
-   * 
+   *
    * \return true if the event must be deleted from the events list, false
    * otherwise (default).
    */
@@ -85,6 +89,16 @@ class GD_CORE_API ArbitraryEventsWorker : private EventVisitor {
                                   bool isCondition) {
     return false;
   };
+
+  /**
+   * Called to do some work on an expression of an event.
+   * \return true if the event must be deleted from the list, false
+   * otherwise (default).
+   */
+  virtual bool DoVisitEventExpression(gd::Expression& expression,
+                                      const gd::ParameterMetadata& metadata) {
+    return false;
+  }
 };
 
 /**
@@ -99,8 +113,7 @@ class GD_CORE_API ArbitraryEventsWorkerWithContext
     : public ArbitraryEventsWorker {
  public:
   ArbitraryEventsWorkerWithContext()
-      : currentGlobalObjectsContainer(nullptr),
-        currentObjectsContainer(nullptr){};
+      : projectScopedContainers(nullptr){};
   virtual ~ArbitraryEventsWorkerWithContext();
 
   /**
@@ -108,30 +121,27 @@ class GD_CORE_API ArbitraryEventsWorkerWithContext
    * giving the objects container on which the events are applying to.
    */
   void Launch(gd::EventsList& events,
-              const gd::ObjectsContainer& globalObjectsContainer_,
-              const gd::ObjectsContainer& objectsContainer_) {
-    currentGlobalObjectsContainer = &globalObjectsContainer_;
-    currentObjectsContainer = &objectsContainer_;
+              const gd::ProjectScopedContainers& projectScopedContainers_) {
+    projectScopedContainers = &projectScopedContainers_;
     ArbitraryEventsWorker::Launch(events);
   };
 
   void Launch(gd::EventsList& events) = delete;
 
  protected:
-  const gd::ObjectsContainer& GetGlobalObjectsContainer() {
+  const gd::ProjectScopedContainers& GetProjectScopedContainers() {
     // Pointers are guaranteed to be not nullptr after
     // Launch was called.
-    return *currentGlobalObjectsContainer;
+    return *projectScopedContainers;
   };
-  const gd::ObjectsContainer& GetObjectsContainer() {
+  const gd::ObjectsContainersList& GetObjectsContainersList() {
     // Pointers are guaranteed to be not nullptr after
     // Launch was called.
-    return *currentObjectsContainer;
+    return projectScopedContainers->GetObjectsContainersList();
   };
 
  private:
-  const gd::ObjectsContainer* currentGlobalObjectsContainer;
-  const gd::ObjectsContainer* currentObjectsContainer;
+  const gd::ProjectScopedContainers* projectScopedContainers;
 };
 
 /**
@@ -162,6 +172,7 @@ protected:
   void VisitInstructionList(const gd::InstructionsList& instructions,
                             bool areConditions);
   void VisitInstruction(const gd::Instruction& instruction, bool isCondition);
+  void VisitEventExpression(const gd::Expression& expression, const gd::ParameterMetadata& metadata);
 
   /**
    * Called to do some work on an event list.
@@ -175,7 +186,7 @@ protected:
 
   /**
    * Called to do some work on a link event.
-   * 
+   *
    * Note that DoVisitEvent is also called with this event.
    */
   virtual void DoVisitLinkEvent(const gd::LinkEvent& linkEvent) {};
@@ -192,6 +203,13 @@ protected:
   virtual void DoVisitInstruction(const gd::Instruction& instruction,
                                   bool isCondition) {};
 
+  /**
+   * Called to do some work on an expression of an event.
+   */
+  virtual void DoVisitEventExpression(const gd::Expression& expression,
+                                      const gd::ParameterMetadata& metadata) {
+  }
+
   bool shouldStopIteration;
 };
 
@@ -207,8 +225,7 @@ class GD_CORE_API ReadOnlyArbitraryEventsWorkerWithContext
     : public ReadOnlyArbitraryEventsWorker {
  public:
   ReadOnlyArbitraryEventsWorkerWithContext()
-      : currentGlobalObjectsContainer(nullptr),
-        currentObjectsContainer(nullptr){};
+      : projectScopedContainers(nullptr){};
   virtual ~ReadOnlyArbitraryEventsWorkerWithContext();
 
   /**
@@ -216,30 +233,22 @@ class GD_CORE_API ReadOnlyArbitraryEventsWorkerWithContext
    * giving the objects container on which the events are applying to.
    */
   void Launch(const gd::EventsList& events,
-              const gd::ObjectsContainer& globalObjectsContainer_,
-              const gd::ObjectsContainer& objectsContainer_) {
-    currentGlobalObjectsContainer = &globalObjectsContainer_;
-    currentObjectsContainer = &objectsContainer_;
+              const gd::ProjectScopedContainers& projectScopedContainers_) {
+    projectScopedContainers = &projectScopedContainers_;
     ReadOnlyArbitraryEventsWorker::Launch(events);
   };
 
   void Launch(gd::EventsList& events) = delete;
 
  protected:
-  const gd::ObjectsContainer& GetGlobalObjectsContainer() {
+  const gd::ProjectScopedContainers& GetProjectScopedContainers() {
     // Pointers are guaranteed to be not nullptr after
     // Launch was called.
-    return *currentGlobalObjectsContainer;
-  };
-  const gd::ObjectsContainer& GetObjectsContainer() {
-    // Pointers are guaranteed to be not nullptr after
-    // Launch was called.
-    return *currentObjectsContainer;
+    return *projectScopedContainers;
   };
 
  private:
-  const gd::ObjectsContainer* currentGlobalObjectsContainer;
-  const gd::ObjectsContainer* currentObjectsContainer;
+  const gd::ProjectScopedContainers* projectScopedContainers;
 };
 
 }  // namespace gd

Core/GDCore/IDE/Events/BehaviorTypeRenamer.cpp

@@ -4,7 +4,6 @@
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/PlatformExtension.h"
 #include "GDCore/IDE/WholeProjectRefactorer.h"
-#include "GDCore/IDE/Events/ExpressionTypeFinder.h"
 #include "GDCore/Project/Behavior.h"
 #include "GDCore/Project/Object.h"
 #include "GDCore/Project/Project.h"

Core/GDCore/IDE/Events/CustomObjectTypeRenamer.cpp

@@ -4,7 +4,6 @@
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/PlatformExtension.h"
 #include "GDCore/IDE/WholeProjectRefactorer.h"
-#include "GDCore/IDE/Events/ExpressionTypeFinder.h"
 #include "GDCore/Project/Behavior.h"
 #include "GDCore/Project/Object.h"
 #include "GDCore/Project/Project.h"

Core/GDCore/IDE/Events/EventsBehaviorRenamer.cpp

@@ -31,14 +31,10 @@ namespace gd {
 class GD_CORE_API ExpressionBehaviorRenamer
     : public ExpressionParser2NodeWorker {
  public:
-  ExpressionBehaviorRenamer(const gd::ObjectsContainer& globalObjectsContainer_,
-                            const gd::ObjectsContainer& objectsContainer_,
-                            const gd::String& objectName_,
+  ExpressionBehaviorRenamer(const gd::String& objectName_,
                             const gd::String& oldBehaviorName_,
                             const gd::String& newBehaviorName_)
       : hasDoneRenaming(false),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
         objectName(objectName_),
         oldBehaviorName(oldBehaviorName_),
         newBehaviorName(newBehaviorName_){};
@@ -97,8 +93,6 @@ class GD_CORE_API ExpressionBehaviorRenamer
 
  private:
   bool hasDoneRenaming;
-  const gd::ObjectsContainer& globalObjectsContainer;
-  const gd::ObjectsContainer& objectsContainer;
   const gd::String& objectName;  // The object name for which the behavior
                                  // must be replaced.
   const gd::String& oldBehaviorName;
@@ -132,9 +126,7 @@ bool EventsBehaviorRenamer::DoVisitInstruction(gd::Instruction& instruction,
         } else {
           auto node = parameterValue.GetRootNode();
           if (node) {
-            ExpressionBehaviorRenamer renamer(GetGlobalObjectsContainer(),
-                                              GetObjectsContainer(),
-                                              objectName,
+            ExpressionBehaviorRenamer renamer(objectName,
                                               oldBehaviorName,
                                               newBehaviorName);
             node->Visit(renamer);

Core/GDCore/IDE/Events/EventsContextAnalyzer.cpp

@@ -19,6 +19,8 @@
 #include "GDCore/IDE/Events/ExpressionTypeFinder.h"
 #include "GDCore/Project/Layout.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/ObjectsContainersList.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/String.h"
 
 namespace gd {
@@ -33,13 +35,11 @@ class GD_CORE_API ExpressionObjectsAnalyzer
  public:
   ExpressionObjectsAnalyzer(
         const gd::Platform &platform_,
-        const gd::ObjectsContainer &globalObjectsContainer_,
-        const gd::ObjectsContainer &objectsContainer_,
+        const gd::ProjectScopedContainers &projectScopedContainers_,
         const gd::String &rootType_,
         EventsContext& context_) :
         platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         rootType(rootType_),
         context(context_){};
   virtual ~ExpressionObjectsAnalyzer(){};
@@ -58,6 +58,25 @@ class GD_CORE_API ExpressionObjectsAnalyzer
   void OnVisitNumberNode(NumberNode& node) override {}
   void OnVisitTextNode(TextNode& node) override {}
   void OnVisitVariableNode(VariableNode& node) override {
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
+
+    if (gd::ParameterMetadata::IsExpression("variable", type)) {
+      // Nothing to do (this can't reference an object)
+    } else {
+      projectScopedContainers.MatchIdentifierWithName<void>(node.name, [&]() {
+          // This is an object variable.
+          context.AddObjectName(projectScopedContainers, node.name);
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
+    }
+
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
@@ -69,26 +88,41 @@ class GD_CORE_API ExpressionObjectsAnalyzer
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitIdentifierNode(IdentifierNode& node) override {
-    auto type = gd::ExpressionTypeFinder::GetType(platform, globalObjectsContainer, objectsContainer, rootType, node);
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
     if (gd::ParameterMetadata::IsObject(type)) {
-      context.AddObjectName(node.identifierName);
+      context.AddObjectName(projectScopedContainers, node.identifierName);
+    } else if (gd::ParameterMetadata::IsExpression("variable", type)) {
+      // Nothing to do (identifier is a variable but not an object).
+    } else {
+      projectScopedContainers.MatchIdentifierWithName<void>(node.identifierName, [&]() {
+          // This is an object variable.
+          context.AddObjectName(projectScopedContainers, node.identifierName);
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
     }
   }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {
     if (!node.objectName.empty()) {
-      context.AddObjectName(node.objectName);
+      context.AddObjectName(projectScopedContainers, node.objectName);
 
       if (!node.behaviorFunctionName.empty()) {
-        context.AddBehaviorName(node.objectName, node.objectFunctionOrBehaviorName);
+        context.AddBehaviorName(projectScopedContainers, node.objectName, node.objectFunctionOrBehaviorName);
       }
     }
   }
   void OnVisitFunctionCallNode(FunctionCallNode& node) override {
     if (!node.objectName.empty()) {
-      context.AddObjectName(node.objectName);
+      context.AddObjectName(projectScopedContainers, node.objectName);
 
       if (!node.behaviorName.empty()) {
-        context.AddBehaviorName(node.objectName, node.behaviorName);
+        context.AddBehaviorName(projectScopedContainers, node.objectName, node.behaviorName);
       }
     }
     for (auto& parameter : node.parameters) {
@@ -99,8 +133,7 @@ class GD_CORE_API ExpressionObjectsAnalyzer
 
  private:
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   const gd::String rootType;
 
   EventsContext& context;
@@ -121,8 +154,7 @@ bool EventsContextAnalyzer::DoVisitInstruction(gd::Instruction& instruction,
              const gd::Expression& parameterValue,
              const gd::String& lastObjectName) {
         AnalyzeParameter(platform,
-                         project,
-                         layout,
+                         GetProjectScopedContainers(),
                          parameterMetadata,
                          parameterValue,
                          context,
@@ -134,8 +166,7 @@ bool EventsContextAnalyzer::DoVisitInstruction(gd::Instruction& instruction,
 
 void EventsContextAnalyzer::AnalyzeParameter(
     const gd::Platform& platform,
-    const gd::ObjectsContainer& project,
-    const gd::ObjectsContainer& layout,
+    const gd::ProjectScopedContainers& projectScopedContainers,
     const gd::ParameterMetadata& metadata,
     const gd::Expression& parameter,
     EventsContext& context,
@@ -143,59 +174,39 @@ void EventsContextAnalyzer::AnalyzeParameter(
   const auto& value = parameter.GetPlainString();
   const auto& type = metadata.GetType();
   if (ParameterMetadata::IsObject(type)) {
-    context.AddObjectName(value);
+    context.AddObjectName(projectScopedContainers, value);
   } else if (ParameterMetadata::IsExpression("number", type)) {
     auto node = parameter.GetRootNode();
 
-    ExpressionObjectsAnalyzer analyzer(platform, project, layout, "number", context);
+    ExpressionObjectsAnalyzer analyzer(platform, projectScopedContainers, "number", context);
     node->Visit(analyzer);
   } else if (ParameterMetadata::IsExpression("string", type)) {
     auto node = parameter.GetRootNode();
 
-    ExpressionObjectsAnalyzer analyzer(platform, project, layout, "string", context);
+    ExpressionObjectsAnalyzer analyzer(platform, projectScopedContainers, "string", context);
     node->Visit(analyzer);
   } else if (ParameterMetadata::IsBehavior(type)) {
-    context.AddBehaviorName(lastObjectName, value);
+    context.AddBehaviorName(projectScopedContainers, lastObjectName, value);
   }
 }
 
-void EventsContext::AddObjectName(const gd::String& objectOrGroupName) {
-  for (auto& realObjectName : ExpandObjectsName(objectOrGroupName)) {
+void EventsContext::AddObjectName(const gd::ProjectScopedContainers& projectScopedContainers,
+                                  const gd::String& objectOrGroupName) {
+  auto& objectsContainersList = projectScopedContainers.GetObjectsContainersList();
+  for (auto& realObjectName : objectsContainersList.ExpandObjectName(objectOrGroupName)) {
     objectNames.insert(realObjectName);
   }
   referencedObjectOrGroupNames.insert(objectOrGroupName);
 }
 
-void EventsContext::AddBehaviorName(const gd::String& objectOrGroupName,
+void EventsContext::AddBehaviorName(const gd::ProjectScopedContainers& projectScopedContainers,
+                                    const gd::String& objectOrGroupName,
                                     const gd::String& behaviorName) {
-  for (auto& realObjectName : ExpandObjectsName(objectOrGroupName)) {
+                                      auto& objectsContainersList = projectScopedContainers.GetObjectsContainersList();
+  for (auto& realObjectName : objectsContainersList.ExpandObjectName(objectOrGroupName)) {
     objectOrGroupBehaviorNames[realObjectName].insert(behaviorName);
   }
   objectOrGroupBehaviorNames[objectOrGroupName].insert(behaviorName);
 }
 
-std::vector<gd::String> EventsContext::ExpandObjectsName(
-    const gd::String& objectName) {
-  // Note: this logic is duplicated in EventsCodeGenerator::ExpandObjectsName
-  std::vector<gd::String> realObjects;
-  if (project.GetObjectGroups().Has(objectName))
-    realObjects =
-        project.GetObjectGroups().Get(objectName).GetAllObjectsNames();
-  else if (layout.GetObjectGroups().Has(objectName))
-    realObjects = layout.GetObjectGroups().Get(objectName).GetAllObjectsNames();
-  else
-    realObjects.push_back(objectName);
-
-  // Ensure that all returned objects actually exists.
-  for (std::size_t i = 0; i < realObjects.size();) {
-    if (!layout.HasObjectNamed(realObjects[i]) &&
-        !project.HasObjectNamed(realObjects[i]))
-      realObjects.erase(realObjects.begin() + i);
-    else
-      ++i;
-  }
-
-  return realObjects;
-}
-
 }  // namespace gd

Core/GDCore/IDE/Events/EventsContextAnalyzer.h

@@ -15,6 +15,7 @@ namespace gd {
 class BaseEvent;
 class Platform;
 class ObjectsContainer;
+class ObjectsContainersList;
 class Project;
 class Layout;
 class EventsList;
@@ -29,12 +30,13 @@ namespace gd {
  */
 class GD_CORE_API EventsContext {
  public:
-  EventsContext(gd::ObjectsContainer& project_, gd::ObjectsContainer& layout_)
-      : project(project_), layout(layout_){};
+  EventsContext(){};
   virtual ~EventsContext(){};
 
-  void AddObjectName(const gd::String& objectOrGroupName);
-  void AddBehaviorName(const gd::String& objectOrGroupName,
+  void AddObjectName(const gd::ProjectScopedContainers& projectScopedContainers,
+                     const gd::String& objectOrGroupName);
+  void AddBehaviorName(const gd::ProjectScopedContainers& projectScopedContainers,
+                       const gd::String& objectOrGroupName,
                        const gd::String& behaviorName);
 
   /**
@@ -59,13 +61,9 @@ class GD_CORE_API EventsContext {
   }
 
  private:
-  std::vector<gd::String> ExpandObjectsName(const gd::String& objectOrGroupName);
-
   std::set<gd::String> referencedObjectOrGroupNames;
   std::set<gd::String> objectNames;
   std::map<gd::String, std::set<gd::String>> objectOrGroupBehaviorNames;
-  gd::ObjectsContainer& project;
-  gd::ObjectsContainer& layout;
 };
 
 /**
@@ -73,15 +71,10 @@ class GD_CORE_API EventsContext {
  *
  * \ingroup IDE
  */
-class GD_CORE_API EventsContextAnalyzer : public ArbitraryEventsWorker {
+class GD_CORE_API EventsContextAnalyzer : public ArbitraryEventsWorkerWithContext {
  public:
-  EventsContextAnalyzer(const gd::Platform& platform_,
-                        gd::ObjectsContainer& project_,
-                        gd::ObjectsContainer& layout_)
-      : platform(platform_),
-        project(project_),
-        layout(layout_),
-        context(project, layout){};
+  EventsContextAnalyzer(const gd::Platform& platform_)
+      : platform(platform_) {};
   virtual ~EventsContextAnalyzer(){};
 
   /**
@@ -90,8 +83,7 @@ class GD_CORE_API EventsContextAnalyzer : public ArbitraryEventsWorker {
   const EventsContext& GetEventsContext() { return context; }
 
   static void AnalyzeParameter(const gd::Platform& platform,
-                               const gd::ObjectsContainer& project,
-                               const gd::ObjectsContainer& layout,
+                               const gd::ProjectScopedContainers& projectScopedContainers,
                                const gd::ParameterMetadata& metadata,
                                const gd::Expression& parameter,
                                EventsContext& context,
@@ -102,8 +94,6 @@ class GD_CORE_API EventsContextAnalyzer : public ArbitraryEventsWorker {
                                   bool isCondition);
 
   const gd::Platform& platform;
-  gd::ObjectsContainer& project;
-  gd::ObjectsContainer& layout;
   EventsContext context;
 };
 

Core/GDCore/IDE/Events/EventsIdentifiersFinder.cpp

@@ -34,14 +34,12 @@ class GD_CORE_API IdentifierFinderExpressionNodeWorker
  public:
   IdentifierFinderExpressionNodeWorker(std::set<gd::String>& results_,
                               const gd::Platform &platform_,
-                              const gd::ObjectsContainer &globalObjectsContainer_,
-                              const gd::ObjectsContainer &objectsContainer_,
+                              const gd::ProjectScopedContainers &projectScopedContainers_,
                               const gd::String& identifierType_,
                               const gd::String& objectName_ = "")
       : results(results_),
         platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         identifierType(identifierType_),
         objectName(objectName_){};
   virtual ~IdentifierFinderExpressionNodeWorker(){};
@@ -79,14 +77,14 @@ class GD_CORE_API IdentifierFinderExpressionNodeWorker
     const gd::ExpressionMetadata &metadata = isObjectFunction ?
             MetadataProvider::GetObjectAnyExpressionMetadata(
                 platform,
-                GetTypeOfObject(globalObjectsContainer, objectsContainer, objectName),
+                projectScopedContainers.GetObjectsContainersList().GetTypeOfObject(objectName),
                 node.functionName):
           MetadataProvider::GetAnyExpressionMetadata(platform, node.functionName);
 
     if (gd::MetadataProvider::IsBadExpressionMetadata(metadata)) {
       return;
     }
-    
+
     size_t parameterIndex = 0;
     for (size_t metadataIndex = (isObjectFunction ? 1 : 0); metadataIndex < metadata.parameters.size()
       && parameterIndex < node.parameters.size(); ++metadataIndex) {
@@ -111,8 +109,7 @@ class GD_CORE_API IdentifierFinderExpressionNodeWorker
 
  private:
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
 
   std::set<gd::String>& results;  ///< Reference to the std::set where argument
                                   ///< values must be stored.
@@ -166,8 +163,7 @@ class GD_CORE_API IdentifierFinderEventWorker
           IdentifierFinderExpressionNodeWorker searcher(
               results,
               platform,
-              GetGlobalObjectsContainer(),
-              GetObjectsContainer(),
+              GetProjectScopedContainers(),
               identifierType,
               objectName);
           node->Visit(searcher);
@@ -227,7 +223,8 @@ void EventsIdentifiersFinder::FindArgumentsInEventsAndDependencies(
                                         platform,
                                         identifierType,
                                         objectName);
-  eventWorker.Launch(layout.GetEvents(), project, layout);
+  eventWorker.Launch(layout.GetEvents(),
+      gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
 
   DependenciesAnalyzer dependenciesAnalyzer = DependenciesAnalyzer(project, layout);
   dependenciesAnalyzer.Analyze();
@@ -238,7 +235,8 @@ void EventsIdentifiersFinder::FindArgumentsInEventsAndDependencies(
                                           platform,
                                           identifierType,
                                           objectName);
-    eventWorker.Launch(externalEvents.GetEvents(), project, layout);
+    eventWorker.Launch(externalEvents.GetEvents(),
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
   }
   for (const gd::String& sceneName : dependenciesAnalyzer.GetScenesDependencies()) {
     const gd::Layout& dependencyLayout = project.GetLayout(sceneName);
@@ -247,7 +245,8 @@ void EventsIdentifiersFinder::FindArgumentsInEventsAndDependencies(
                                           platform,
                                           identifierType,
                                           objectName);
-    eventWorker.Launch(dependencyLayout.GetEvents(), project, dependencyLayout);
+    eventWorker.Launch(dependencyLayout.GetEvents(),
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, dependencyLayout));
   }
 }
 

Core/GDCore/IDE/Events/EventsPropertyReplacer.cpp

@@ -0,0 +1,277 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "GDCore/IDE/Events/EventsPropertyReplacer.h"
+
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "GDCore/Events/Event.h"
+#include "GDCore/Events/EventsList.h"
+#include "GDCore/Events/Parsers/ExpressionParser2NodePrinter.h"
+#include "GDCore/Events/Parsers/ExpressionParser2NodeWorker.h"
+#include "GDCore/Extensions/Metadata/MetadataProvider.h"
+#include "GDCore/Extensions/Metadata/ParameterMetadata.h"
+#include "GDCore/Extensions/Metadata/ParameterMetadataTools.h"
+#include "GDCore/IDE/Events/ExpressionValidator.h"
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
+#include "GDCore/Project/PropertiesContainer.h"
+#include "GDCore/String.h"
+#include "GDCore/Tools/Log.h"
+
+namespace gd {
+
+/**
+ * \brief Go through the nodes and rename properties,
+ * or signal if the instruction must be renamed if a removed property is used.
+ *
+ * \see gd::ExpressionParser2
+ */
+class GD_CORE_API ExpressionPropertyReplacer
+    : public ExpressionParser2NodeWorker {
+ public:
+  ExpressionPropertyReplacer(
+      const gd::Platform& platform_,
+      const gd::ProjectScopedContainers& projectScopedContainers_,
+      const gd::PropertiesContainer& targetPropertiesContainer_,
+      const std::unordered_map<gd::String, gd::String>& oldToNewPropertyNames_,
+      const std::unordered_set<gd::String>& removedPropertyNames_)
+      : hasDoneRenaming(false),
+        removedPropertyUsed(false),
+        platform(platform_),
+        projectScopedContainers(projectScopedContainers_),
+        targetPropertiesContainer(targetPropertiesContainer_),
+        oldToNewPropertyNames(oldToNewPropertyNames_),
+        removedPropertyNames(removedPropertyNames_){};
+  virtual ~ExpressionPropertyReplacer(){};
+
+  bool HasDoneRenaming() const { return hasDoneRenaming; }
+  bool IsRemovedPropertyUsed() const { return removedPropertyUsed; }
+
+ protected:
+  void OnVisitSubExpressionNode(SubExpressionNode& node) override {
+    node.expression->Visit(*this);
+  }
+  void OnVisitOperatorNode(OperatorNode& node) override {
+    node.leftHandSide->Visit(*this);
+    node.rightHandSide->Visit(*this);
+  }
+  void OnVisitUnaryOperatorNode(UnaryOperatorNode& node) override {
+    node.factor->Visit(*this);
+  }
+  void OnVisitNumberNode(NumberNode& node) override {}
+  void OnVisitTextNode(TextNode& node) override {}
+  void OnVisitVariableNode(VariableNode& node) override {
+    auto& propertiesContainersList =
+        projectScopedContainers.GetPropertiesContainersList();
+
+    // The node represents a variable or an object name on which a variable
+    // will be accessed, or a property with a child.
+
+    // Match the potential *new* name of the property, because refactorings are
+    // done after changes in the variables container.
+    projectScopedContainers.MatchIdentifierWithName<void>(
+      GetPotentialNewName(node.name),
+      [&]() {
+        // Do nothing, it's an object variable.
+        if (node.child) node.child->Visit(*this);
+      }, [&]() {
+        // Do nothing, it's a variable.
+        if (node.child) node.child->Visit(*this);
+      }, [&]() {
+        // This is a property, check if it's coming from the target container with
+        // properties to replace.
+        if (propertiesContainersList.HasPropertiesContainer(
+                targetPropertiesContainer)) {
+          // The node represents a property, that can come from the target
+          // (because the target is in the scope), replace or remove it:
+          RenameOrRemovePropertyOfTargetPropertyContainer(node.name);
+        }
+
+        if (node.child) node.child->Visit(*this);
+      }, [&]() {
+        // Do nothing, it's a parameter.
+        if (node.child) node.child->Visit(*this);
+      }, [&]() {
+        // This is something else - potentially a deleted property.
+        // Check if it's coming from the target container with
+        // properties to replace.
+        if (propertiesContainersList.HasPropertiesContainer(
+                targetPropertiesContainer)) {
+          // The node represents a property, that can come from the target
+          // (because the target is in the scope), replace or remove it:
+          RenameOrRemovePropertyOfTargetPropertyContainer(node.name);
+        }
+
+        if (node.child) node.child->Visit(*this);
+      });
+  }
+  void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
+    if (node.child) node.child->Visit(*this);
+  }
+  void OnVisitVariableBracketAccessorNode(
+      VariableBracketAccessorNode& node) override {
+    node.expression->Visit(*this);
+    if (node.child) node.child->Visit(*this);
+  }
+  void OnVisitIdentifierNode(IdentifierNode& node) override {
+    auto& propertiesContainersList =
+        projectScopedContainers.GetPropertiesContainersList();
+
+    // Match the potential *new* name of the property, because refactorings are
+    // done after changes in the variables container.
+    projectScopedContainers.MatchIdentifierWithName<void>(
+      GetPotentialNewName(node.identifierName),
+      [&]() {
+        // Do nothing, it's an object variable.
+      }, [&]() {
+        // Do nothing, it's a variable.
+      }, [&]() {
+        // This is a property, check if it's coming from the target container with
+        // properties to replace.
+        if (propertiesContainersList.HasPropertiesContainer(
+                targetPropertiesContainer)) {
+          // The node represents a property, that can come from the target
+          // (because the target is in the scope), replace or remove it:
+          RenameOrRemovePropertyOfTargetPropertyContainer(node.identifierName);
+        }
+      }, [&]() {
+        // Do nothing, it's a parameter.
+      }, [&]() {
+        // This is something else - potentially a deleted property.
+        // Check if it's coming from the target container with
+        // properties to replace.
+        if (propertiesContainersList.HasPropertiesContainer(
+                targetPropertiesContainer)) {
+          // The node represents a property, that can come from the target
+          // (because the target is in the scope), replace or remove it:
+          RenameOrRemovePropertyOfTargetPropertyContainer(node.identifierName);
+        }
+      });
+  }
+  void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {}
+  void OnVisitFunctionCallNode(FunctionCallNode& node) override {
+    for (auto& parameter : node.parameters) {
+      parameter->Visit(*this);
+    }
+  }
+  void OnVisitEmptyNode(EmptyNode& node) override {}
+
+ private:
+  bool hasDoneRenaming;
+  bool removedPropertyUsed;
+
+  const gd::String& GetPotentialNewName(const gd::String& oldName) {
+    return oldToNewPropertyNames.count(oldName) >= 1
+            ? oldToNewPropertyNames.find(oldName)->second
+            : oldName;
+  }
+
+  bool RenameOrRemovePropertyOfTargetPropertyContainer(
+      gd::String& propertyName) {
+    if (oldToNewPropertyNames.count(propertyName) >= 1) {
+      propertyName = oldToNewPropertyNames.find(propertyName)->second;
+      hasDoneRenaming = true;
+      return true;
+    } else if (removedPropertyNames.count(propertyName) >= 1) {
+      removedPropertyUsed = true;
+      return true;
+    }
+
+    return false;  // Nothing was changed or done.
+  }
+
+  // Scope:
+  const gd::Platform& platform;
+  const gd::ProjectScopedContainers& projectScopedContainers;
+
+  // Renaming or removing to do:
+  const gd::PropertiesContainer& targetPropertiesContainer;
+  const std::unordered_map<gd::String, gd::String>& oldToNewPropertyNames;
+  const std::unordered_set<gd::String>& removedPropertyNames;
+
+  gd::String objectNameToUseForVariableAccessor;
+};
+
+bool EventsPropertyReplacer::DoVisitInstruction(gd::Instruction& instruction,
+                                                bool isCondition) {
+  const auto& metadata = isCondition
+                             ? gd::MetadataProvider::GetConditionMetadata(
+                                   platform, instruction.GetType())
+                             : gd::MetadataProvider::GetActionMetadata(
+                                   platform, instruction.GetType());
+  bool shouldDeleteInstruction = false;
+
+  gd::ParameterMetadataTools::IterateOverParametersWithIndex(
+      instruction.GetParameters(),
+      metadata.GetParameters(),
+      [&](const gd::ParameterMetadata& parameterMetadata,
+          const gd::Expression& parameterValue,
+          size_t parameterIndex,
+          const gd::String& lastObjectName) {
+        const gd::String& type = parameterMetadata.GetType();
+
+        if (!gd::ParameterMetadata::IsExpression("variable", type) &&
+            !gd::ParameterMetadata::IsExpression("number", type) &&
+            !gd::ParameterMetadata::IsExpression("string", type))
+          return;  // Not an expression that can contain properties.
+
+        auto node = parameterValue.GetRootNode();
+        if (node) {
+          ExpressionPropertyReplacer renamer(platform,
+                                             GetProjectScopedContainers(),
+                                             targetPropertiesContainer,
+                                             oldToNewPropertyNames,
+                                             removedPropertyNames);
+          node->Visit(renamer);
+
+          if (renamer.IsRemovedPropertyUsed()) {
+            shouldDeleteInstruction = true;
+          } else if (renamer.HasDoneRenaming()) {
+            instruction.SetParameter(
+                parameterIndex, ExpressionParser2NodePrinter::PrintNode(*node));
+          }
+        }
+      });
+
+  return shouldDeleteInstruction;
+}
+
+bool EventsPropertyReplacer::DoVisitEventExpression(
+    gd::Expression& expression, const gd::ParameterMetadata& metadata) {
+  const gd::String& type = metadata.GetType();
+
+  if (!gd::ParameterMetadata::IsExpression("variable", type) &&
+      !gd::ParameterMetadata::IsExpression("number", type) &&
+      !gd::ParameterMetadata::IsExpression("string", type))
+    return false;  // Not an expression that can contain properties.
+
+  auto node = expression.GetRootNode();
+  if (node) {
+    ExpressionPropertyReplacer renamer(platform,
+                                       GetProjectScopedContainers(),
+                                       targetPropertiesContainer,
+                                       oldToNewPropertyNames,
+                                       removedPropertyNames);
+    node->Visit(renamer);
+
+    if (renamer.IsRemovedPropertyUsed()) {
+      return true;
+    } else if (renamer.HasDoneRenaming()) {
+      expression = ExpressionParser2NodePrinter::PrintNode(*node);
+    }
+  }
+
+  return false;
+}
+
+EventsPropertyReplacer::~EventsPropertyReplacer() {}
+
+}  // namespace gd

Core/GDCore/IDE/Events/EventsPropertyReplacer.h

@@ -0,0 +1,56 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#pragma once
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "GDCore/IDE/Events/ArbitraryEventsWorker.h"
+#include "GDCore/String.h"
+namespace gd {
+class BaseEvent;
+class PropertiesContainer;
+class EventsList;
+class Platform;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief Replace in expressions and in parameters of actions or conditions,
+ * references to the name of a property by another.
+ *
+ * \ingroup IDE
+ */
+class GD_CORE_API EventsPropertyReplacer
+    : public ArbitraryEventsWorkerWithContext {
+ public:
+  EventsPropertyReplacer(
+      const gd::Platform &platform_,
+      const gd::PropertiesContainer &targetPropertiesContainer_,
+      const std::unordered_map<gd::String, gd::String> &oldToNewPropertyNames_,
+      const std::unordered_set<gd::String> &removedPropertyNames_)
+      : platform(platform_),
+        targetPropertiesContainer(targetPropertiesContainer_),
+        oldToNewPropertyNames(oldToNewPropertyNames_),
+        removedPropertyNames(removedPropertyNames_){};
+  virtual ~EventsPropertyReplacer();
+
+ private:
+  bool DoVisitInstruction(gd::Instruction &instruction,
+                          bool isCondition) override;
+  bool DoVisitEventExpression(gd::Expression &expression,
+                              const gd::ParameterMetadata &metadata) override;
+
+  const gd::Platform &platform;
+  const gd::PropertiesContainer &targetPropertiesContainer;
+  const std::unordered_map<gd::String, gd::String> &oldToNewPropertyNames;
+  const std::unordered_set<gd::String> &removedPropertyNames;
+};
+
+}  // namespace gd

Core/GDCore/IDE/Events/EventsRefactorer.cpp

@@ -20,6 +20,7 @@
 #include "GDCore/IDE/Events/InstructionSentenceFormatter.h"
 #include "GDCore/Project/ObjectsContainer.h"
 #include "GDCore/Project/EventsBasedObject.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/IDE/Events/ExpressionTypeFinder.h"
 
 using namespace std;
@@ -36,14 +37,12 @@ const gd::String EventsRefactorer::searchIgnoredCharacters = ";:,#()";
 class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
  public:
   ExpressionObjectRenamer(const gd::Platform &platform_,
-                          const gd::ObjectsContainer &globalObjectsContainer_,
-                          const gd::ObjectsContainer &objectsContainer_,
+                          const gd::ProjectScopedContainers& projectScopedContainers_,
                           const gd::String &rootType_,
                           const gd::String& objectName_,
                           const gd::String& objectNewName_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         rootType(rootType_),
         hasDoneRenaming(false),
         objectName(objectName_),
@@ -51,14 +50,13 @@ class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
   virtual ~ExpressionObjectRenamer(){};
 
   static bool Rename(const gd::Platform &platform,
-                     const gd::ObjectsContainer &globalObjectsContainer,
-                     const gd::ObjectsContainer &objectsContainer,
+                     const gd::ProjectScopedContainers &projectScopedContainers,
                      const gd::String &rootType,
                      gd::ExpressionNode& node,
                      const gd::String& objectName,
                      const gd::String& objectNewName) {
-    if (gd::ExpressionValidator::HasNoErrors(platform, globalObjectsContainer, objectsContainer, rootType, node)) {
-      ExpressionObjectRenamer renamer(platform, globalObjectsContainer, objectsContainer, rootType, objectName, objectNewName);
+    if (gd::ExpressionValidator::HasNoErrors(platform, projectScopedContainers, rootType, node)) {
+      ExpressionObjectRenamer renamer(platform, projectScopedContainers, rootType, objectName, objectNewName);
       node.Visit(renamer);
 
       return renamer.HasDoneRenaming();
@@ -83,6 +81,28 @@ class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
   void OnVisitNumberNode(NumberNode& node) override {}
   void OnVisitTextNode(TextNode& node) override {}
   void OnVisitVariableNode(VariableNode& node) override {
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
+
+    if (gd::ValueTypeMetadata::IsTypeLegacyPreScopedVariable(type)) {
+      // Nothing to do (this can't reference an object)
+    } else {
+      if (node.name == objectName) {
+        projectScopedContainers.MatchIdentifierWithName<void>(node.name, [&]() {
+          // This is an object variable.
+          hasDoneRenaming = true;
+          node.name = objectNewName;
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
+      }
+    }
+
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
@@ -94,11 +114,29 @@ class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitIdentifierNode(IdentifierNode& node) override {
-    auto type = gd::ExpressionTypeFinder::GetType(platform, globalObjectsContainer, objectsContainer, rootType, node);
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
     if (gd::ParameterMetadata::IsObject(type) &&
         node.identifierName == objectName) {
       hasDoneRenaming = true;
       node.identifierName = objectNewName;
+    } else if (gd::ValueTypeMetadata::IsTypeLegacyPreScopedVariable(type)) {
+      // Nothing to do (this can't reference an object)
+    } else {
+      if (node.identifierName == objectName) {
+        projectScopedContainers.MatchIdentifierWithName<void>(node.identifierName, [&]() {
+          // This is an object variable.
+          hasDoneRenaming = true;
+          node.identifierName = objectNewName;
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
+      }
     }
   }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {
@@ -124,8 +162,7 @@ class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
   const gd::String& objectNewName;
 
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   const gd::String rootType;
 };
 
@@ -138,26 +175,23 @@ class GD_CORE_API ExpressionObjectRenamer : public ExpressionParser2NodeWorker {
 class GD_CORE_API ExpressionObjectFinder : public ExpressionParser2NodeWorker {
  public:
   ExpressionObjectFinder(const gd::Platform &platform_,
-                         const gd::ObjectsContainer &globalObjectsContainer_,
-                         const gd::ObjectsContainer &objectsContainer_,
+                         const gd::ProjectScopedContainers &projectScopedContainers_,
                          const gd::String &rootType_,
-                         const gd::String& objectName_)
+                         const gd::String& searchedObjectName_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         rootType(rootType_),
         hasObject(false),
-        objectName(objectName_){};
+        searchedObjectName(searchedObjectName_){};
   virtual ~ExpressionObjectFinder(){};
 
   static bool CheckIfHasObject(const gd::Platform &platform,
-                               const gd::ObjectsContainer &globalObjectsContainer,
-                               const gd::ObjectsContainer &objectsContainer,
+                               const gd::ProjectScopedContainers &projectScopedContainers,
                                const gd::String &rootType,
                                gd::ExpressionNode& node,
                                const gd::String& objectName) {
-    if (gd::ExpressionValidator::HasNoErrors(platform, globalObjectsContainer, objectsContainer, rootType, node)) {
-      ExpressionObjectFinder finder(platform, globalObjectsContainer, objectsContainer, rootType, objectName);
+    if (gd::ExpressionValidator::HasNoErrors(platform, projectScopedContainers, rootType, node)) {
+      ExpressionObjectFinder finder(platform, projectScopedContainers, rootType, objectName);
       node.Visit(finder);
 
       return finder.HasFoundObject();
@@ -182,6 +216,27 @@ class GD_CORE_API ExpressionObjectFinder : public ExpressionParser2NodeWorker {
   void OnVisitNumberNode(NumberNode& node) override {}
   void OnVisitTextNode(TextNode& node) override {}
   void OnVisitVariableNode(VariableNode& node) override {
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
+
+    if (gd::ValueTypeMetadata::IsTypeLegacyPreScopedVariable(type)) {
+      // Nothing to do (this can't reference an object)
+    } else {
+      if (node.name == searchedObjectName) {
+        projectScopedContainers.MatchIdentifierWithName<void>(node.name, [&]() {
+          // This is an object variable.
+          hasObject = true;
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
+      }
+    }
+
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
@@ -193,19 +248,36 @@ class GD_CORE_API ExpressionObjectFinder : public ExpressionParser2NodeWorker {
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitIdentifierNode(IdentifierNode& node) override {
-    auto type = gd::ExpressionTypeFinder::GetType(platform, globalObjectsContainer, objectsContainer, rootType, node);
+    auto type = gd::ExpressionTypeFinder::GetType(platform, projectScopedContainers, rootType, node);
     if (gd::ParameterMetadata::IsObject(type) &&
-        node.identifierName == objectName) {
+        node.identifierName == searchedObjectName) {
       hasObject = true;
+    } else if (gd::ValueTypeMetadata::IsTypeLegacyPreScopedVariable(type)) {
+      // Nothing to do (this can't reference an object)
+    } else {
+      if (node.identifierName == searchedObjectName) {
+        projectScopedContainers.MatchIdentifierWithName<void>(node.identifierName, [&]() {
+          // This is an object variable.
+          hasObject = true;
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+        }, [&]() {
+          // This is a parameter.
+        }, [&]() {
+          // This is something else.
+        });
+      }
     }
   }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {
-    if (node.objectName == objectName) {
+    if (node.objectName == searchedObjectName) {
       hasObject = true;
     }
   }
   void OnVisitFunctionCallNode(FunctionCallNode& node) override {
-    if (node.objectName == objectName) {
+    if (node.objectName == searchedObjectName) {
       hasObject = true;
     }
     for (auto& parameter : node.parameters) {
@@ -216,17 +288,15 @@ class GD_CORE_API ExpressionObjectFinder : public ExpressionParser2NodeWorker {
 
  private:
   bool hasObject;
-  const gd::String& objectName;
+  const gd::String& searchedObjectName;
 
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   const gd::String rootType;
 };
 
 bool EventsRefactorer::RenameObjectInActions(const gd::Platform& platform,
-                                             gd::ObjectsContainer& project,
-                                             gd::ObjectsContainer& layout,
+                                             gd::ProjectScopedContainers& projectScopedContainers,
                                              gd::InstructionsList& actions,
                                              gd::String oldName,
                                              gd::String newName) {
@@ -245,7 +315,7 @@ bool EventsRefactorer::RenameObjectInActions(const gd::Platform& platform,
                    "number", instrInfos.parameters[pNb].GetType())) {
         auto node = actions[aId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectRenamer::Rename(platform, project, layout, "number", *node, oldName, newName)) {
+        if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "number", *node, oldName, newName)) {
           actions[aId].SetParameter(
               pNb, ExpressionParser2NodePrinter::PrintNode(*node));
         }
@@ -255,7 +325,7 @@ bool EventsRefactorer::RenameObjectInActions(const gd::Platform& platform,
                    "string", instrInfos.parameters[pNb].GetType())) {
         auto node = actions[aId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectRenamer::Rename(platform, project, layout, "string", *node, oldName, newName)) {
+        if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "string", *node, oldName, newName)) {
           actions[aId].SetParameter(
               pNb, ExpressionParser2NodePrinter::PrintNode(*node));
         }
@@ -265,8 +335,7 @@ bool EventsRefactorer::RenameObjectInActions(const gd::Platform& platform,
     if (!actions[aId].GetSubInstructions().empty())
       somethingModified =
           RenameObjectInActions(platform,
-                                project,
-                                layout,
+                                projectScopedContainers,
                                 actions[aId].GetSubInstructions(),
                                 oldName,
                                 newName) ||
@@ -278,8 +347,7 @@ bool EventsRefactorer::RenameObjectInActions(const gd::Platform& platform,
 
 bool EventsRefactorer::RenameObjectInConditions(
     const gd::Platform& platform,
-    gd::ObjectsContainer& project,
-    gd::ObjectsContainer& layout,
+    gd::ProjectScopedContainers& projectScopedContainers,
     gd::InstructionsList& conditions,
     gd::String oldName,
     gd::String newName) {
@@ -299,7 +367,7 @@ bool EventsRefactorer::RenameObjectInConditions(
                    "number", instrInfos.parameters[pNb].GetType())) {
         auto node = conditions[cId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectRenamer::Rename(platform, project, layout, "number", *node, oldName, newName)) {
+        if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "number", *node, oldName, newName)) {
           conditions[cId].SetParameter(
               pNb, ExpressionParser2NodePrinter::PrintNode(*node));
         }
@@ -309,7 +377,7 @@ bool EventsRefactorer::RenameObjectInConditions(
                    "string", instrInfos.parameters[pNb].GetType())) {
         auto node = conditions[cId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectRenamer::Rename(platform, project, layout, "string", *node, oldName, newName)) {
+        if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "string", *node, oldName, newName)) {
           conditions[cId].SetParameter(
               pNb, ExpressionParser2NodePrinter::PrintNode(*node));
         }
@@ -319,8 +387,7 @@ bool EventsRefactorer::RenameObjectInConditions(
     if (!conditions[cId].GetSubInstructions().empty())
       somethingModified =
           RenameObjectInConditions(platform,
-                                   project,
-                                   layout,
+                                   projectScopedContainers,
                                    conditions[cId].GetSubInstructions(),
                                    oldName,
                                    newName) ||
@@ -332,8 +399,7 @@ bool EventsRefactorer::RenameObjectInConditions(
 
 bool EventsRefactorer::RenameObjectInEventParameters(
     const gd::Platform& platform,
-    gd::ObjectsContainer& project,
-    gd::ObjectsContainer& layout,
+    gd::ProjectScopedContainers& projectScopedContainers,
     gd::Expression& expression,
     gd::ParameterMetadata parameterMetadata,
     gd::String oldName,
@@ -348,7 +414,7 @@ bool EventsRefactorer::RenameObjectInEventParameters(
                                            parameterMetadata.GetType())) {
     auto node = expression.GetRootNode();
 
-    if (ExpressionObjectRenamer::Rename(platform, project, layout, "number", *node, oldName, newName)) {
+    if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "number", *node, oldName, newName)) {
       expression = ExpressionParser2NodePrinter::PrintNode(*node);
     }
   }
@@ -357,7 +423,7 @@ bool EventsRefactorer::RenameObjectInEventParameters(
                                            parameterMetadata.GetType())) {
     auto node = expression.GetRootNode();
 
-    if (ExpressionObjectRenamer::Rename(platform, project, layout, "string", *node, oldName, newName)) {
+    if (ExpressionObjectRenamer::Rename(platform, projectScopedContainers, "string", *node, oldName, newName)) {
       expression = ExpressionParser2NodePrinter::PrintNode(*node);
     }
   }
@@ -366,8 +432,7 @@ bool EventsRefactorer::RenameObjectInEventParameters(
 }
 
 void EventsRefactorer::RenameObjectInEvents(const gd::Platform& platform,
-                                            gd::ObjectsContainer& project,
-                                            gd::ObjectsContainer& layout,
+                                            gd::ProjectScopedContainers& projectScopedContainers,
                                             gd::EventsList& events,
                                             gd::String oldName,
                                             gd::String newName) {
@@ -376,14 +441,14 @@ void EventsRefactorer::RenameObjectInEvents(const gd::Platform& platform,
         events[i].GetAllConditionsVectors();
     for (std::size_t j = 0; j < conditionsVectors.size(); ++j) {
       bool somethingModified = RenameObjectInConditions(
-          platform, project, layout, *conditionsVectors[j], oldName, newName);
+          platform, projectScopedContainers, *conditionsVectors[j], oldName, newName);
     }
 
     vector<gd::InstructionsList*> actionsVectors =
         events[i].GetAllActionsVectors();
     for (std::size_t j = 0; j < actionsVectors.size(); ++j) {
       bool somethingModified = RenameObjectInActions(
-          platform, project, layout, *actionsVectors[j], oldName, newName);
+          platform, projectScopedContainers, *actionsVectors[j], oldName, newName);
     }
 
     vector<pair<gd::Expression*, gd::ParameterMetadata>>
@@ -393,8 +458,7 @@ void EventsRefactorer::RenameObjectInEvents(const gd::Platform& platform,
       gd::ParameterMetadata parameterMetadata =
           expressionsWithMetadata[j].second;
       bool somethingModified = RenameObjectInEventParameters(platform,
-                                                             project,
-                                                             layout,
+                                                             projectScopedContainers,
                                                              *expression,
                                                              parameterMetadata,
                                                              oldName,
@@ -403,8 +467,7 @@ void EventsRefactorer::RenameObjectInEvents(const gd::Platform& platform,
 
     if (events[i].CanHaveSubEvents())
       RenameObjectInEvents(platform,
-                           project,
-                           layout,
+                           projectScopedContainers,
                            events[i].GetSubEvents(),
                            oldName,
                            newName);
@@ -412,8 +475,7 @@ void EventsRefactorer::RenameObjectInEvents(const gd::Platform& platform,
 }
 
 bool EventsRefactorer::RemoveObjectInActions(const gd::Platform& platform,
-                                             gd::ObjectsContainer& globalObjectsContainer,
-                                             gd::ObjectsContainer& objectsContainer,
+                                             gd::ProjectScopedContainers& projectScopedContainers,
                                              gd::InstructionsList& actions,
                                              gd::String name) {
   bool somethingModified = false;
@@ -435,7 +497,7 @@ bool EventsRefactorer::RemoveObjectInActions(const gd::Platform& platform,
                    "number", instrInfos.parameters[pNb].GetType())) {
         auto node = actions[aId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectFinder::CheckIfHasObject(platform, globalObjectsContainer, objectsContainer, "number", *node, name)) {
+        if (ExpressionObjectFinder::CheckIfHasObject(platform, projectScopedContainers, "number", *node, name)) {
           deleteMe = true;
           break;
         }
@@ -445,7 +507,7 @@ bool EventsRefactorer::RemoveObjectInActions(const gd::Platform& platform,
                    "string", instrInfos.parameters[pNb].GetType())) {
         auto node = actions[aId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectFinder::CheckIfHasObject(platform, globalObjectsContainer, objectsContainer, "string", *node, name)) {
+        if (ExpressionObjectFinder::CheckIfHasObject(platform, projectScopedContainers, "string", *node, name)) {
           deleteMe = true;
           break;
         }
@@ -459,8 +521,7 @@ bool EventsRefactorer::RemoveObjectInActions(const gd::Platform& platform,
     } else if (!actions[aId].GetSubInstructions().empty())
       somethingModified =
           RemoveObjectInActions(platform,
-                                globalObjectsContainer,
-                                objectsContainer,
+                                projectScopedContainers,
                                 actions[aId].GetSubInstructions(),
                                 name) ||
           somethingModified;
@@ -471,8 +532,7 @@ bool EventsRefactorer::RemoveObjectInActions(const gd::Platform& platform,
 
 bool EventsRefactorer::RemoveObjectInConditions(
     const gd::Platform& platform,
-    gd::ObjectsContainer& globalObjectsContainer,
-    gd::ObjectsContainer& objectsContainer,
+    gd::ProjectScopedContainers& projectScopedContainers,
     gd::InstructionsList& conditions,
     gd::String name) {
   bool somethingModified = false;
@@ -495,7 +555,7 @@ bool EventsRefactorer::RemoveObjectInConditions(
                    "number", instrInfos.parameters[pNb].GetType())) {
         auto node = conditions[cId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectFinder::CheckIfHasObject(platform, globalObjectsContainer, objectsContainer, "number", *node, name)) {
+        if (ExpressionObjectFinder::CheckIfHasObject(platform, projectScopedContainers, "number", *node, name)) {
           deleteMe = true;
           break;
         }
@@ -505,7 +565,7 @@ bool EventsRefactorer::RemoveObjectInConditions(
                    "string", instrInfos.parameters[pNb].GetType())) {
         auto node = conditions[cId].GetParameter(pNb).GetRootNode();
 
-        if (ExpressionObjectFinder::CheckIfHasObject(platform, globalObjectsContainer, objectsContainer, "string", *node, name)) {
+        if (ExpressionObjectFinder::CheckIfHasObject(platform, projectScopedContainers, "string", *node, name)) {
           deleteMe = true;
           break;
         }
@@ -519,8 +579,7 @@ bool EventsRefactorer::RemoveObjectInConditions(
     } else if (!conditions[cId].GetSubInstructions().empty())
       somethingModified =
           RemoveObjectInConditions(platform,
-                                   globalObjectsContainer,
-                                   objectsContainer,
+                                   projectScopedContainers,
                                    conditions[cId].GetSubInstructions(),
                                    name) ||
           somethingModified;
@@ -530,8 +589,7 @@ bool EventsRefactorer::RemoveObjectInConditions(
 }
 
 void EventsRefactorer::RemoveObjectInEvents(const gd::Platform& platform,
-                                            gd::ObjectsContainer& globalObjectsContainer,
-                                            gd::ObjectsContainer& objectsContainer,
+                                            gd::ProjectScopedContainers& projectScopedContainers,
                                             gd::EventsList& events,
                                             gd::String name) {
   for (std::size_t i = 0; i < events.size(); ++i) {
@@ -539,19 +597,19 @@ void EventsRefactorer::RemoveObjectInEvents(const gd::Platform& platform,
         events[i].GetAllConditionsVectors();
     for (std::size_t j = 0; j < conditionsVectors.size(); ++j) {
       bool conditionsModified = RemoveObjectInConditions(
-          platform, globalObjectsContainer, objectsContainer, *conditionsVectors[j], name);
+          platform, projectScopedContainers, *conditionsVectors[j], name);
     }
 
     vector<gd::InstructionsList*> actionsVectors =
         events[i].GetAllActionsVectors();
     for (std::size_t j = 0; j < actionsVectors.size(); ++j) {
       bool actionsModified = RemoveObjectInActions(
-          platform, globalObjectsContainer, objectsContainer, *actionsVectors[j], name);
+          platform, projectScopedContainers, *actionsVectors[j], name);
     }
 
     if (events[i].CanHaveSubEvents())
       RemoveObjectInEvents(
-          platform, globalObjectsContainer, objectsContainer, events[i].GetSubEvents(), name);
+          platform, projectScopedContainers, events[i].GetSubEvents(), name);
   }
 }
 
@@ -587,20 +645,20 @@ std::vector<EventsSearchResult> EventsRefactorer::ReplaceStringInEvents(
   for (std::size_t i = 0; i < events.size(); ++i) {
     bool eventModified = false;
 
-    std::vector<gd::Expression*> allObjectExpressions =
-        events[i].GetAllObjectExpressions();
-    for (std::size_t j = 0; j < allObjectExpressions.size(); ++j) {
+    auto allExpressionsWithMetadata = events[i].GetAllExpressionsWithMetadata();
+    for (auto& expressionAndMetadata : allExpressionsWithMetadata) {
+      gd::Expression* expression = expressionAndMetadata.first;
+
       gd::String newExpressionPlainString =
-          matchCase ? allObjectExpressions[j]->GetPlainString().FindAndReplace(
+          matchCase ? expression->GetPlainString().FindAndReplace(
                           toReplace, newString, true)
                     : ReplaceAllOccurrencesCaseInsensitive(
-                          allObjectExpressions[j]->GetPlainString(),
+                          expression->GetPlainString(),
                           toReplace,
                           newString);
 
-      if (newExpressionPlainString !=
-          allObjectExpressions[j]->GetPlainString()) {
-        *allObjectExpressions[j] = gd::Expression(newExpressionPlainString);
+      if (newExpressionPlainString != expression->GetPlainString()) {
+        *expression = gd::Expression(newExpressionPlainString);
 
         if (!eventModified) {
           modifiedEvents.push_back(EventsSearchResult(
@@ -815,14 +873,14 @@ vector<EventsSearchResult> EventsRefactorer::SearchInEvents(
   for (std::size_t i = 0; i < events.size(); ++i) {
     bool eventAddedInResults = false;
 
-    std::vector<gd::Expression*> allObjectExpressions =
-        events[i].GetAllObjectExpressions();
-    for (std::size_t j = 0; j < allObjectExpressions.size(); ++j) {
+    auto allExpressionsWithMetadata = events[i].GetAllExpressionsWithMetadata();
+    for (auto& expressionAndMetadata : allExpressionsWithMetadata) {
+      gd::Expression* expression = expressionAndMetadata.first;
+
       size_t foundPosition =
           matchCase
-              ? allObjectExpressions[j]->GetPlainString().find(search)
-              : allObjectExpressions[j]->GetPlainString().FindCaseInsensitive(
-                    search);
+              ? expression->GetPlainString().find(search)
+              : expression->GetPlainString().FindCaseInsensitive(search);
 
       if (foundPosition != gd::String::npos && !eventAddedInResults) {
         results.push_back(EventsSearchResult(

Core/GDCore/IDE/Events/EventsRefactorer.h

@@ -14,6 +14,8 @@
 namespace gd {
 class EventsList;
 class ObjectsContainer;
+class ObjectsContainersList;
+class ProjectScopedContainers;
 class Platform;
 class ExternalEvents;
 class BaseEvent;
@@ -79,8 +81,7 @@ class GD_CORE_API EventsRefactorer {
    * events ).
    */
   static void RenameObjectInEvents(const gd::Platform& platform,
-                                   gd::ObjectsContainer& project,
-                                   gd::ObjectsContainer& layout,
+                                   gd::ProjectScopedContainers& projectScopedContainers,
                                    gd::EventsList& events,
                                    gd::String oldName,
                                    gd::String newName);
@@ -89,8 +90,7 @@ class GD_CORE_API EventsRefactorer {
    * Remove all actions or conditions using an object
    */
   static void RemoveObjectInEvents(const gd::Platform& platform,
-                                   gd::ObjectsContainer& project,
-                                   gd::ObjectsContainer& layout,
+                                   gd::ProjectScopedContainers& projectScopedContainers,
                                    gd::EventsList& events,
                                    gd::String name);
 
@@ -136,8 +136,7 @@ class GD_CORE_API EventsRefactorer {
    * \return true if something was modified.
    */
   static bool RenameObjectInActions(const gd::Platform& platform,
-                                    gd::ObjectsContainer& project,
-                                    gd::ObjectsContainer& layout,
+                                    gd::ProjectScopedContainers& projectScopedContainers,
                                     gd::InstructionsList& instructions,
                                     gd::String oldName,
                                     gd::String newName);
@@ -149,8 +148,7 @@ class GD_CORE_API EventsRefactorer {
    * \return true if something was modified.
    */
   static bool RenameObjectInConditions(const gd::Platform& platform,
-                                       gd::ObjectsContainer& project,
-                                       gd::ObjectsContainer& layout,
+                                       gd::ProjectScopedContainers& projectScopedContainers,
                                        gd::InstructionsList& instructions,
                                        gd::String oldName,
                                        gd::String newName);
@@ -163,8 +161,7 @@ class GD_CORE_API EventsRefactorer {
    */
   static bool RenameObjectInEventParameters(
       const gd::Platform& platform,
-      gd::ObjectsContainer& project,
-      gd::ObjectsContainer& layout,
+      gd::ProjectScopedContainers& projectScopedContainers,
       gd::Expression& expression,
       gd::ParameterMetadata parameterMetadata,
       gd::String oldName,
@@ -176,8 +173,7 @@ class GD_CORE_API EventsRefactorer {
    * \return true if something was modified.
    */
   static bool RemoveObjectInConditions(const gd::Platform& platform,
-                                       gd::ObjectsContainer& project,
-                                       gd::ObjectsContainer& layout,
+                                       gd::ProjectScopedContainers& projectScopedContainers,
                                        gd::InstructionsList& conditions,
                                        gd::String name);
 
@@ -187,8 +183,7 @@ class GD_CORE_API EventsRefactorer {
    * \return true if something was modified.
    */
   static bool RemoveObjectInActions(const gd::Platform& platform,
-                                    gd::ObjectsContainer& project,
-                                    gd::ObjectsContainer& layout,
+                                    gd::ProjectScopedContainers& projectScopedContainers,
                                     gd::InstructionsList& conditions,
                                     gd::String name);
 

Core/GDCore/IDE/Events/EventsVariableReplacer.cpp

@@ -0,0 +1,404 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "GDCore/IDE/Events/EventsVariableReplacer.h"
+
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "GDCore/Events/Event.h"
+#include "GDCore/Events/EventsList.h"
+#include "GDCore/Events/Parsers/ExpressionParser2NodePrinter.h"
+#include "GDCore/Events/Parsers/ExpressionParser2NodeWorker.h"
+#include "GDCore/Extensions/Metadata/MetadataProvider.h"
+#include "GDCore/Extensions/Metadata/ParameterMetadata.h"
+#include "GDCore/Extensions/Metadata/ParameterMetadataTools.h"
+#include "GDCore/IDE/Events/ExpressionValidator.h"
+#include "GDCore/IDE/Events/ExpressionVariableOwnerFinder.h"
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
+#include "GDCore/Project/VariablesContainer.h"
+#include "GDCore/String.h"
+#include "GDCore/Tools/Log.h"
+
+namespace gd {
+
+/**
+ * \brief Go through the nodes and rename variables,
+ * or signal if the instruction must be renamed if a removed variable is used.
+ *
+ * \see gd::ExpressionParser2
+ */
+class GD_CORE_API ExpressionVariableReplacer
+    : public ExpressionParser2NodeWorker {
+ public:
+  ExpressionVariableReplacer(
+      const gd::Platform& platform_,
+      const gd::ProjectScopedContainers& projectScopedContainers_,
+      const gd::VariablesContainer& targetVariablesContainer_,
+      const std::unordered_map<gd::String, gd::String>& oldToNewVariableNames_,
+      const std::unordered_set<gd::String>& removedVariableNames_)
+      : hasDoneRenaming(false),
+        removedVariableUsed(false),
+        platform(platform_),
+        projectScopedContainers(projectScopedContainers_),
+        forcedInitialVariablesContainer(nullptr),
+        targetVariablesContainer(targetVariablesContainer_),
+        oldToNewVariableNames(oldToNewVariableNames_),
+        removedVariableNames(removedVariableNames_){};
+  virtual ~ExpressionVariableReplacer(){};
+
+  void SetForcedInitialVariablesContainer(
+      const gd::VariablesContainer* forcedInitialVariablesContainer_) {
+    forcedInitialVariablesContainer = forcedInitialVariablesContainer_;
+  }
+
+  bool HasDoneRenaming() const { return hasDoneRenaming; }
+  bool IsRemovedVariableUsed() const { return removedVariableUsed; }
+
+ protected:
+  void OnVisitSubExpressionNode(SubExpressionNode& node) override {
+    node.expression->Visit(*this);
+  }
+  void OnVisitOperatorNode(OperatorNode& node) override {
+    node.leftHandSide->Visit(*this);
+    node.rightHandSide->Visit(*this);
+  }
+  void OnVisitUnaryOperatorNode(UnaryOperatorNode& node) override {
+    node.factor->Visit(*this);
+  }
+  void OnVisitNumberNode(NumberNode& node) override {}
+  void OnVisitTextNode(TextNode& node) override {}
+  void OnVisitVariableNode(VariableNode& node) override {
+    // The node represents a variable or an object name on which a variable
+    // will be accessed.
+
+    if (forcedInitialVariablesContainer) {
+      // A scope was forced. Honor it: it means this node represents a variable
+      // of the forced variables container.
+      if (forcedInitialVariablesContainer == &targetVariablesContainer) {
+        RenameOrRemoveVariableOfTargetVariableContainer(node.name);
+      }
+
+      if (node.child) node.child->Visit(*this);
+      return;
+    }
+
+    // Match the potential *new* name of the variable, because refactorings are
+    // done after changes in the variables container.
+    projectScopedContainers.MatchIdentifierWithName<void>(
+        GetPotentialNewName(node.name),
+        [&]() {
+          // This represents an object.
+          // Remember the object name.
+          objectNameToUseForVariableAccessor = node.name;
+          if (node.child) node.child->Visit(*this);
+          objectNameToUseForVariableAccessor = "";
+        },
+        [&]() {
+          // This is a variable.
+          if (projectScopedContainers.GetVariablesContainersList()
+                  .HasVariablesContainer(targetVariablesContainer)) {
+            // The node represents a variable, that can come from the target
+            // (because the target is in the scope), replace or remove it:
+            RenameOrRemoveVariableOfTargetVariableContainer(node.name);
+          }
+
+          if (node.child) node.child->Visit(*this);
+        },
+        [&]() {
+          // This is a property.
+          if (node.child) node.child->Visit(*this);
+        },
+        [&]() {
+          // This is a parameter.
+          if (node.child) node.child->Visit(*this);
+        },
+        [&]() {
+          // This is something else - potentially a deleted variable.
+          if (projectScopedContainers.GetVariablesContainersList()
+                  .HasVariablesContainer(targetVariablesContainer)) {
+            // The node represents a variable, that can come from the target
+            // (because the target is in the scope), replace or remove it:
+            RenameOrRemoveVariableOfTargetVariableContainer(node.name);
+          }
+
+          if (node.child) node.child->Visit(*this);
+        });
+  }
+  void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
+    auto& objectsContainersList =
+        projectScopedContainers.GetObjectsContainersList();
+    if (!objectNameToUseForVariableAccessor.empty()) {
+      if (objectsContainersList.HasVariablesContainer(
+              objectNameToUseForVariableAccessor, targetVariablesContainer)) {
+        // The node represents an object variable, and this object variables are
+        // the target. Do the replacement or removals:
+        RenameOrRemoveVariableOfTargetVariableContainer(node.name);
+      }
+    }
+    objectNameToUseForVariableAccessor = "";
+
+    if (node.child) node.child->Visit(*this);
+  }
+  void OnVisitVariableBracketAccessorNode(
+      VariableBracketAccessorNode& node) override {
+    objectNameToUseForVariableAccessor = "";
+
+    node.expression->Visit(*this);
+    if (node.child) node.child->Visit(*this);
+  }
+  void OnVisitIdentifierNode(IdentifierNode& node) override {
+    auto& objectsContainersList =
+        projectScopedContainers.GetObjectsContainersList();
+
+    // The node represents a variable or an object variable in an expression
+    // (and if it's a variable reference or a value does not have any importance
+    // here).
+
+    if (forcedInitialVariablesContainer) {
+      // A scope was forced. Honor it: it means this node represents a variable
+      // of the forced variables container.
+      if (forcedInitialVariablesContainer == &targetVariablesContainer) {
+        RenameOrRemoveVariableOfTargetVariableContainer(node.identifierName);
+      }
+      return;
+    }
+
+    // Match the potential *new* name of the variable, because refactorings are
+    // done after changes in the variables container.
+    projectScopedContainers.MatchIdentifierWithName<void>(
+        GetPotentialNewName(node.identifierName),
+        [&]() {
+          // This represents an object.
+          if (objectsContainersList.HasVariablesContainer(
+                  node.identifierName, targetVariablesContainer)) {
+            // The node represents an object variable, and this object variables
+            // are the target. Do the replacement or removals:
+            RenameOrRemoveVariableOfTargetVariableContainer(
+                node.childIdentifierName);
+          }
+        },
+        [&]() {
+          // This is a variable.
+          if (projectScopedContainers.GetVariablesContainersList()
+                  .HasVariablesContainer(targetVariablesContainer)) {
+            // The node represents a variable, that can come from the target
+            // (because the target is in the scope), replace or remove it:
+            RenameOrRemoveVariableOfTargetVariableContainer(
+                node.identifierName);
+          }
+        },
+        [&]() {
+          // This is a property.
+        },
+        [&]() {
+          // This is a parameter.
+        },
+        [&]() {
+          // This is something else - potentially a deleted variable.
+          if (projectScopedContainers.GetVariablesContainersList()
+                  .HasVariablesContainer(targetVariablesContainer)) {
+            // The node represents a variable, that can come from the target
+            // (because the target is in the scope), replace or remove it:
+            RenameOrRemoveVariableOfTargetVariableContainer(
+                node.identifierName);
+          }
+        });
+  }
+  void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {}
+  void OnVisitFunctionCallNode(FunctionCallNode& node) override {
+    const gd::ExpressionMetadata& metadata =
+        MetadataProvider::GetFunctionCallMetadata(
+            platform, projectScopedContainers.GetObjectsContainersList(), node);
+
+    for (size_t parameterIndex = 0; parameterIndex < node.parameters.size();
+         ++parameterIndex) {
+      const gd::ParameterMetadata* parameterMetadata =
+          MetadataProvider::GetFunctionCallParameterMetadata(
+              platform,
+              projectScopedContainers.GetObjectsContainersList(),
+              node,
+              parameterIndex);
+
+      // Handle legacy pre-scoped variable parameters: in this case, we
+      // force the "scope" at which starts the evalution of variables.
+      if (parameterMetadata && parameterMetadata->GetValueTypeMetadata()
+                                   .IsLegacyPreScopedVariable()) {
+        const gd::VariablesContainer* oldForcedInitialVariablesContainer =
+            forcedInitialVariablesContainer;
+
+        forcedInitialVariablesContainer = nullptr;
+        if (parameterMetadata->GetType() == "globalvar") {
+          forcedInitialVariablesContainer =
+              projectScopedContainers.GetVariablesContainersList()
+                  .GetTopMostVariablesContainer();
+        } else if (parameterMetadata->GetType() == "scenevar") {
+          forcedInitialVariablesContainer =
+              projectScopedContainers.GetVariablesContainersList()
+                  .GetBottomMostVariablesContainer();
+        } else if (parameterMetadata->GetType() == "objectvar") {
+          auto objectName = gd::ExpressionVariableOwnerFinder::GetObjectName(
+              platform,
+              projectScopedContainers.GetObjectsContainersList(),
+              node.objectName,
+              *node.parameters[parameterIndex].get());
+          forcedInitialVariablesContainer =
+              projectScopedContainers.GetObjectsContainersList()
+                  .GetObjectOrGroupVariablesContainer(objectName);
+        }
+
+        node.parameters[parameterIndex]->Visit(*this);
+        forcedInitialVariablesContainer = oldForcedInitialVariablesContainer;
+      } else {
+        // For any other parameter, there is no special treatment being needed.
+        node.parameters[parameterIndex]->Visit(*this);
+      }
+    }
+  }
+  void OnVisitEmptyNode(EmptyNode& node) override {}
+
+ private:
+  bool hasDoneRenaming;
+  bool removedVariableUsed;
+
+  const gd::String& GetPotentialNewName(const gd::String& oldName) {
+    return oldToNewVariableNames.count(oldName) >= 1
+            ? oldToNewVariableNames.find(oldName)->second
+            : oldName;
+  }
+
+  bool RenameOrRemoveVariableOfTargetVariableContainer(
+      gd::String& variableName) {
+    if (oldToNewVariableNames.count(variableName) >= 1) {
+      variableName = oldToNewVariableNames.find(variableName)->second;
+      hasDoneRenaming = true;
+      return true;
+    } else if (removedVariableNames.count(variableName) >= 1) {
+      removedVariableUsed = true;
+      return true;
+    }
+
+    return false;  // Nothing was changed or done.
+  }
+
+  // Scope:
+  const gd::Platform& platform;
+  const gd::ProjectScopedContainers& projectScopedContainers;
+  const gd::VariablesContainer* forcedInitialVariablesContainer;
+
+  // Renaming or removing to do:
+  const gd::VariablesContainer& targetVariablesContainer;
+  const std::unordered_map<gd::String, gd::String>& oldToNewVariableNames;
+  const std::unordered_set<gd::String>& removedVariableNames;
+
+  gd::String objectNameToUseForVariableAccessor;
+};
+
+const gd::VariablesContainer*
+EventsVariableReplacer::FindForcedVariablesContainerIfAny(
+    const gd::String& type, const gd::String& lastObjectName) {
+  // Handle legacy pre-scoped variable parameters: in this case, we
+  // force the "scope" at which starts the evalution of variables.
+  if (type == "objectvar") {
+    return GetProjectScopedContainers()
+        .GetObjectsContainersList()
+        .GetObjectOrGroupVariablesContainer(lastObjectName);
+  } else if (type == "globalvar") {
+    return GetProjectScopedContainers()
+        .GetVariablesContainersList()
+        .GetTopMostVariablesContainer();
+  } else if (type == "scenevar") {
+    return GetProjectScopedContainers()
+        .GetVariablesContainersList()
+        .GetBottomMostVariablesContainer();
+  }
+
+  return nullptr;
+}
+
+bool EventsVariableReplacer::DoVisitInstruction(gd::Instruction& instruction,
+                                                bool isCondition) {
+  const auto& metadata = isCondition
+                             ? gd::MetadataProvider::GetConditionMetadata(
+                                   platform, instruction.GetType())
+                             : gd::MetadataProvider::GetActionMetadata(
+                                   platform, instruction.GetType());
+  bool shouldDeleteInstruction = false;
+
+  gd::ParameterMetadataTools::IterateOverParametersWithIndex(
+      instruction.GetParameters(),
+      metadata.GetParameters(),
+      [&](const gd::ParameterMetadata& parameterMetadata,
+          const gd::Expression& parameterValue,
+          size_t parameterIndex,
+          const gd::String& lastObjectName) {
+        const gd::String& type = parameterMetadata.GetType();
+
+        if (!gd::ParameterMetadata::IsExpression("variable", type) &&
+            !gd::ParameterMetadata::IsExpression("number", type) &&
+            !gd::ParameterMetadata::IsExpression("string", type))
+          return;  // Not an expression that can contain variables.
+
+        auto node = parameterValue.GetRootNode();
+        if (node) {
+          ExpressionVariableReplacer renamer(platform,
+                                             GetProjectScopedContainers(),
+                                             targetVariablesContainer,
+                                             oldToNewVariableNames,
+                                             removedVariableNames);
+          renamer.SetForcedInitialVariablesContainer(
+              FindForcedVariablesContainerIfAny(type, lastObjectName));
+          node->Visit(renamer);
+
+          if (renamer.IsRemovedVariableUsed()) {
+            shouldDeleteInstruction = true;
+          } else if (renamer.HasDoneRenaming()) {
+            instruction.SetParameter(
+                parameterIndex, ExpressionParser2NodePrinter::PrintNode(*node));
+          }
+        }
+      });
+
+  return shouldDeleteInstruction;
+}
+
+bool EventsVariableReplacer::DoVisitEventExpression(
+    gd::Expression& expression, const gd::ParameterMetadata& metadata) {
+  const gd::String& type = metadata.GetType();
+
+  if (!gd::ParameterMetadata::IsExpression("variable", type) &&
+      !gd::ParameterMetadata::IsExpression("number", type) &&
+      !gd::ParameterMetadata::IsExpression("string", type))
+    return false;  // Not an expression that can contain variables.
+
+  auto node = expression.GetRootNode();
+  if (node) {
+    ExpressionVariableReplacer renamer(platform,
+                                       GetProjectScopedContainers(),
+                                       targetVariablesContainer,
+                                       oldToNewVariableNames,
+                                       removedVariableNames);
+    renamer.SetForcedInitialVariablesContainer(
+        FindForcedVariablesContainerIfAny(type, ""));
+    node->Visit(renamer);
+
+    if (renamer.IsRemovedVariableUsed()) {
+      return true;
+    } else if (renamer.HasDoneRenaming()) {
+      expression = ExpressionParser2NodePrinter::PrintNode(*node);
+    }
+  }
+
+  return false;
+}
+
+EventsVariableReplacer::~EventsVariableReplacer() {}
+
+}  // namespace gd

Core/GDCore/IDE/Events/EventsVariableReplacer.h

@@ -0,0 +1,60 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#pragma once
+#include <map>
+#include <memory>
+#include <unordered_map>
+#include <unordered_set>
+#include <vector>
+
+#include "GDCore/IDE/Events/ArbitraryEventsWorker.h"
+#include "GDCore/String.h"
+namespace gd {
+class BaseEvent;
+class VariablesContainer;
+class EventsList;
+class Platform;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief Replace in expressions and in parameters of actions or conditions,
+ * references to the name of a variable by another.
+ *
+ * \ingroup IDE
+ */
+class GD_CORE_API EventsVariableReplacer
+    : public ArbitraryEventsWorkerWithContext {
+ public:
+  EventsVariableReplacer(
+      const gd::Platform &platform_,
+      const gd::VariablesContainer &targetVariablesContainer_,
+      const std::unordered_map<gd::String, gd::String> &oldToNewVariableNames_,
+      const std::unordered_set<gd::String> &removedVariableNames_)
+      : platform(platform_),
+        targetVariablesContainer(targetVariablesContainer_),
+        oldToNewVariableNames(oldToNewVariableNames_),
+        removedVariableNames(removedVariableNames_){};
+  virtual ~EventsVariableReplacer();
+
+ private:
+  bool DoVisitInstruction(gd::Instruction &instruction,
+                          bool isCondition) override;
+  bool DoVisitEventExpression(gd::Expression &expression,
+                              const gd::ParameterMetadata &metadata) override;
+
+  const gd::VariablesContainer *FindForcedVariablesContainerIfAny(
+      const gd::String &type, const gd::String &lastObjectName);
+
+  const gd::Platform &platform;
+  const gd::VariablesContainer &targetVariablesContainer;
+  gd::String objectName;
+  const std::unordered_map<gd::String, gd::String> &oldToNewVariableNames;
+  const std::unordered_set<gd::String> &removedVariableNames;
+};
+
+}  // namespace gd

Core/GDCore/IDE/Events/EventsVariablesFinder.cpp

@@ -17,6 +17,7 @@
 #include "GDCore/Project/Layout.h"
 #include "GDCore/Project/Object.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/Project/ExternalEvents.h"
 #include "GDCore/IDE/DependenciesAnalyzer.h"
 
@@ -34,14 +35,12 @@ class GD_CORE_API VariableFinderExpressionNodeWorker
  public:
   VariableFinderExpressionNodeWorker(std::set<gd::String>& results_,
                               const gd::Platform &platform_,
-                              const gd::ObjectsContainer &globalObjectsContainer_,
-                              const gd::ObjectsContainer &objectsContainer_,
+                              const gd::ProjectScopedContainers &projectScopedContainers_,
                               const gd::String& parameterType_,
                               const gd::String& objectName_ = "")
       : results(results_),
         platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         parameterType(parameterType_),
         objectName(objectName_){};
   virtual ~VariableFinderExpressionNodeWorker(){};
@@ -60,6 +59,9 @@ class GD_CORE_API VariableFinderExpressionNodeWorker
   void OnVisitNumberNode(NumberNode& node) override {}
   void OnVisitTextNode(TextNode& node) override {}
   void OnVisitVariableNode(VariableNode& node) override {
+    // We don't check variables or object variables here, because object variables only work
+    // if the variable is already declared.
+
     if (node.child) node.child->Visit(*this);
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
@@ -70,7 +72,10 @@ class GD_CORE_API VariableFinderExpressionNodeWorker
     node.expression->Visit(*this);
     if (node.child) node.child->Visit(*this);
   }
-  void OnVisitIdentifierNode(IdentifierNode& node) override {}
+  void OnVisitIdentifierNode(IdentifierNode& node) override {
+    // We don't check object variables here, because object variables only work
+    // if the variable is already declared.
+  }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {}
   void OnVisitFunctionCallNode(FunctionCallNode& node) override {
     bool considerFunction = objectName.empty() || node.objectName == objectName;
@@ -79,7 +84,7 @@ class GD_CORE_API VariableFinderExpressionNodeWorker
     const gd::ExpressionMetadata &metadata = isObjectFunction ?
             MetadataProvider::GetObjectAnyExpressionMetadata(
                 platform,
-                GetTypeOfObject(globalObjectsContainer, objectsContainer, objectName),
+                projectScopedContainers.GetObjectsContainersList().GetTypeOfObject(objectName),
                 node.functionName):
             MetadataProvider::GetAnyExpressionMetadata(platform, node.functionName);
 
@@ -110,8 +115,7 @@ class GD_CORE_API VariableFinderExpressionNodeWorker
 
  private:
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
 
   std::set<gd::String>& results;  ///< Reference to the std::set where argument
                                   ///< values must be stored.
@@ -163,8 +167,7 @@ class GD_CORE_API VariableFinderEventWorker
           VariableFinderExpressionNodeWorker searcher(
               results,
               platform,
-              GetGlobalObjectsContainer(),
-              GetObjectsContainer(),
+              GetProjectScopedContainers(),
               parameterType,
               objectName);
           node->Visit(searcher);
@@ -252,7 +255,8 @@ void EventsVariablesFinder::FindArgumentsInEventsAndDependencies(
                                         platform,
                                         parameterType,
                                         objectName);
-  eventWorker.Launch(layout.GetEvents(), project, layout);
+  eventWorker.Launch(layout.GetEvents(),
+      gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
 
   DependenciesAnalyzer dependenciesAnalyzer = DependenciesAnalyzer(project, layout);
   dependenciesAnalyzer.Analyze();
@@ -263,7 +267,8 @@ void EventsVariablesFinder::FindArgumentsInEventsAndDependencies(
                                           platform,
                                           parameterType,
                                           objectName);
-    eventWorker.Launch(externalEvents.GetEvents(), project, layout);
+    eventWorker.Launch(externalEvents.GetEvents(),
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout));
   }
   for (const gd::String& sceneName : dependenciesAnalyzer.GetScenesDependencies()) {
     const gd::Layout& dependencyLayout = project.GetLayout(sceneName);
@@ -272,7 +277,8 @@ void EventsVariablesFinder::FindArgumentsInEventsAndDependencies(
                                           platform,
                                           parameterType,
                                           objectName);
-    eventWorker.Launch(dependencyLayout.GetEvents(), project, dependencyLayout);
+    eventWorker.Launch(dependencyLayout.GetEvents(),
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, dependencyLayout));
   }
 }
 

Core/GDCore/IDE/Events/ExpressionCompletionFinder.cpp

@@ -10,21 +10,15 @@ namespace gd {
 const gd::ParameterMetadata
     ExpressionCompletionDescription::badParameterMetadata;
 
+const gd::ObjectConfiguration
+    ExpressionCompletionDescription::badObjectConfiguration;
+
 /**
  * \brief Turn an ExpressionCompletionDescription to a string.
  */
 std::ostream& operator<<(std::ostream& os,
                          ExpressionCompletionDescription const& value) {
-  os << "{ " << value.GetCompletionKind() << ", " << value.GetType() << ", "
-     << value.GetPrefix() << ", " << value.GetObjectName() << ", "
-     << value.GetBehaviorName() << ", "
-     << (value.IsExact() ? "exact" : "non-exact") << ", "
-     << (value.IsLastParameter() ? "last parameter" : "not last parameter")
-     << ", "
-     << (value.HasParameterMetadata()
-             ? gd::String::From(&value.GetParameterMetadata())
-             : "no parameter metadata")
-     << " }";
+  os << value.ToString();
   return os;
 }
 

Core/GDCore/IDE/Events/ExpressionLeftSideTypeFinder.h

@@ -14,7 +14,7 @@
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/Metadata/ObjectMetadata.h"
 #include "GDCore/Extensions/Metadata/ParameterMetadata.h"
-#include "GDCore/Project/Layout.h"  // For GetTypeOfObject and GetTypeOfBehavior
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/Tools/Localization.h"
 
 namespace gd {
@@ -40,11 +40,10 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
    * operations.
    */
   static const gd::String GetType(const gd::Platform &platform,
-                      const gd::ObjectsContainer &globalObjectsContainer,
-                      const gd::ObjectsContainer &objectsContainer,
+                      const gd::ProjectScopedContainers &projectScopedContainers,
                       gd::ExpressionNode& node) {
     gd::ExpressionLeftSideTypeFinder typeFinder(
-        platform, globalObjectsContainer, objectsContainer);
+        platform, projectScopedContainers);
     node.Visit(typeFinder);
     return typeFinder.GetType();
   }
@@ -53,11 +52,9 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
 
  protected:
   ExpressionLeftSideTypeFinder(const gd::Platform &platform_,
-                       const gd::ObjectsContainer &globalObjectsContainer_,
-                       const gd::ObjectsContainer &objectsContainer_)
+                       const gd::ProjectScopedContainers &projectScopedContainers_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         type("unknown") {};
 
   const gd::String &GetType() {
@@ -69,6 +66,14 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
   }
   void OnVisitOperatorNode(OperatorNode& node) override {
     node.leftHandSide->Visit(*this);
+
+    // The type is decided by the first operand, unless it can (`number|string`)
+    // or should (`unknown`) be refined, in which case we go for the right
+    // operand (which got visited knowing the type of the first operand, so it's
+    // equal or strictly more precise than the left operand).
+    if (type == "unknown" || type == "number|string") {
+      node.rightHandSide->Visit(*this);
+    }
   }
   void OnVisitUnaryOperatorNode(UnaryOperatorNode& node) override {
     node.factor->Visit(*this);
@@ -85,7 +90,7 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
   }
   void OnVisitFunctionCallNode(FunctionCallNode& node) override {
     const gd::ExpressionMetadata &metadata = MetadataProvider::GetFunctionCallMetadata(
-        platform, globalObjectsContainer, objectsContainer, node);
+        platform, projectScopedContainers.GetObjectsContainersList(), node);
     if (gd::MetadataProvider::IsBadExpressionMetadata(metadata)) {
       type = "unknown";
     }
@@ -95,12 +100,99 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
   }
   void OnVisitVariableNode(VariableNode& node) override {
     type = "unknown";
+
+    projectScopedContainers.MatchIdentifierWithName<void>(node.name,
+      [&]() {
+        // This represents an object.
+        // We could store it to explore the type of the variable, but in practice this
+        // is only called for structures/arrays with 2 levels, and we don't support structure
+        // type identification for now.
+      },
+      [&]() {
+        // This is a variable.
+        // We could store it to explore the type of the variable, but in practice this
+        // is only called for structures/arrays with 2 levels, and we don't support structure
+        // type identification for now.
+      }, [&]() {
+        // This is a property with more than one child - this is unsupported.
+      }, [&]() {
+        // This is a parameter with more than one child - this is unsupported.
+      }, [&]() {
+        // This is something else.
+        type = "unknown";
+      });
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
     type = "unknown";
   }
   void OnVisitIdentifierNode(IdentifierNode& node) override {
     type = "unknown";
+    projectScopedContainers.MatchIdentifierWithName<void>(node.identifierName,
+      [&]() {
+        // It's an object variable.
+        if (projectScopedContainers.GetObjectsContainersList()
+                .HasObjectOrGroupWithVariableNamed(
+                    node.identifierName, node.childIdentifierName)
+              == ObjectsContainersList::VariableExistence::DoesNotExist) {
+          type = "unknown";
+          return;
+        }
+
+        auto variableType =
+            projectScopedContainers.GetObjectsContainersList()
+                .GetTypeOfObjectOrGroupVariable(node.identifierName,
+                                                node.childIdentifierName);
+        ReadTypeFromVariable(variableType);
+      },
+      [&]() {
+        // It's a variable.
+        const auto& variable =
+            projectScopedContainers.GetVariablesContainersList().Get(
+                node.identifierName);
+
+        if (node.childIdentifierName.empty()) {
+          ReadTypeFromVariable(variable.GetType());
+        } else {
+          if (!variable.HasChild(node.childIdentifierName)) {
+            type = "unknown";
+            return;
+          }
+
+          ReadTypeFromVariable(
+              variable.GetChild(node.childIdentifierName).GetType());
+        }
+      }, [&]() {
+        // This is a property.
+        const gd::NamedPropertyDescriptor& property = projectScopedContainers
+            .GetPropertiesContainersList().Get(node.identifierName).second;
+
+        if (property.GetType() == "Number") {
+          type = "number";
+        } else if (property.GetType() == "Boolean") {
+          // Nothing - we don't know the precise type (this could be used a string or as a number)
+        } else {
+          // Assume type is String or equivalent.
+          type = "string";
+        }
+      }, [&]() {
+        // It's a parameter.
+
+        const auto& parametersVectorsList = projectScopedContainers.GetParametersVectorsList();
+        const auto& parameter = gd::ParameterMetadataTools::Get(parametersVectorsList, node.identifierName);
+        const auto& valueTypeMetadata = parameter.GetValueTypeMetadata();
+        if (valueTypeMetadata.IsNumber()) {
+          type = "number";
+        } else if (valueTypeMetadata.IsString()) {
+          type = "string";
+        } else if (valueTypeMetadata.IsBoolean()) {
+          // Nothing - we don't know the precise type (this could be used as a string or as a number).
+        } else {
+          type = "unknown";
+        }
+      }, [&]() {
+        // This is something else.
+        type = "unknown";
+      });
   }
   void OnVisitEmptyNode(EmptyNode& node) override {
     type = "unknown";
@@ -110,11 +202,18 @@ class GD_CORE_API ExpressionLeftSideTypeFinder : public ExpressionParser2NodeWor
   }
 
  private:
+  void ReadTypeFromVariable(gd::Variable::Type variableType) {
+    if (variableType == gd::Variable::Number) {
+      type = "number";
+    } else if (variableType == gd::Variable::String) {
+      type = "string";
+    }
+  }
+
   gd::String type;
 
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   const gd::String rootType;
 };
 

Core/GDCore/IDE/Events/ExpressionTypeFinder.h

@@ -15,7 +15,7 @@
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/Metadata/ObjectMetadata.h"
 #include "GDCore/Extensions/Metadata/ParameterMetadata.h"
-#include "GDCore/Project/Layout.h" // For GetTypeOfObject and GetTypeOfBehavior
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/Tools/Localization.h"
 
 namespace gd {
@@ -31,7 +31,7 @@ namespace gd {
 /**
  * \brief Find the type of the expression or sub-expression that a given node
  * represents.
- * 
+ *
  * The type returned by this worker is a mix of:
  * - an expected type looking up like a parameter declaration
  * - an actual type looking down, but only looking at the most left branch
@@ -50,12 +50,11 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
    * sub-expression that a given node represents.
    */
   static const gd::String GetType(const gd::Platform &platform,
-                      const gd::ObjectsContainer &globalObjectsContainer,
-                      const gd::ObjectsContainer &objectsContainer,
+                      const gd::ProjectScopedContainers &projectScopedContainers,
                       const gd::String &rootType,
                       gd::ExpressionNode& node) {
     gd::ExpressionTypeFinder typeFinder(
-        platform, globalObjectsContainer, objectsContainer, rootType);
+        platform, projectScopedContainers, rootType);
     node.Visit(typeFinder);
     return typeFinder.GetType();
   }
@@ -64,12 +63,10 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
 
  protected:
   ExpressionTypeFinder(const gd::Platform &platform_,
-                       const gd::ObjectsContainer &globalObjectsContainer_,
-                       const gd::ObjectsContainer &objectsContainer_,
+                       const gd::ProjectScopedContainers &projectScopedContainers_,
                        const gd::String &rootType_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         rootType(rootType_),
         type(ExpressionTypeFinder::unknownType),
         child(nullptr) {};
@@ -114,10 +111,13 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
       type = ExpressionTypeFinder::unknownType;
     }
     auto leftSideType = gd::ExpressionLeftSideTypeFinder::GetType(
-        platform, 
-        globalObjectsContainer,
-        objectsContainer,
+        platform,
+        projectScopedContainers,
         node);
+
+    // If we can infer a definitive number or string type, use it.
+    // Otherwise, we only know that it's number or string, and this can even
+    // be used as is at runtime.
     if (leftSideType == ExpressionTypeFinder::numberType
      || leftSideType == ExpressionTypeFinder::stringType) {
       type = leftSideType;
@@ -129,7 +129,7 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
   void OnVisitFunctionCallNode(FunctionCallNode& node) override {
     if (child == nullptr) {
       const gd::ExpressionMetadata &metadata = MetadataProvider::GetFunctionCallMetadata(
-          platform, globalObjectsContainer, objectsContainer, node);
+          platform, projectScopedContainers.GetObjectsContainersList(), node);
       if (gd::MetadataProvider::IsBadExpressionMetadata(metadata)) {
         VisitParent(node);
       }
@@ -141,8 +141,7 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
       const gd::ParameterMetadata* parameterMetadata =
           gd::MetadataProvider::GetFunctionCallParameterMetadata(
               platform,
-              globalObjectsContainer,
-              objectsContainer,
+              projectScopedContainers.GetObjectsContainersList(),
               node,
               *child);
       if (parameterMetadata == nullptr || parameterMetadata->GetType().empty()) {
@@ -162,9 +161,8 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
     }
     else if (rootType == ExpressionTypeFinder::numberOrStringType) {
       auto leftSideType = gd::ExpressionLeftSideTypeFinder::GetType(
-          platform, 
-          globalObjectsContainer,
-          objectsContainer,
+          platform,
+          projectScopedContainers,
           node);
       if (leftSideType == ExpressionTypeFinder::numberType
        || leftSideType == ExpressionTypeFinder::stringType) {
@@ -188,8 +186,7 @@ class GD_CORE_API ExpressionTypeFinder : public ExpressionParser2NodeWorker {
   ExpressionNode *child;
 
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   const gd::String rootType;
 };
 

Core/GDCore/IDE/Events/ExpressionValidator.cpp

@@ -11,16 +11,20 @@
 
 #include "GDCore/CommonTools.h"
 #include "GDCore/Events/Expression.h"
+#include "GDCore/Events/Parsers/ExpressionParser2.h"
 #include "GDCore/Extensions/Metadata/ExpressionMetadata.h"
 #include "GDCore/Extensions/Metadata/InstructionMetadata.h"
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/Metadata/ObjectMetadata.h"
 #include "GDCore/Extensions/Platform.h"
 #include "GDCore/Project/Layout.h"
+#include "GDCore/Project/ObjectsContainersList.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
+#include "GDCore/Project/Variable.h"
+#include "GDCore/Project/VariablesContainersList.h"
 #include "GDCore/Tools/Localization.h"
 #include "GDCore/Tools/MakeUnique.h"
-#include "GDCore/Events/Parsers/ExpressionParser2.h"
 
 using namespace std;
 
@@ -59,61 +63,212 @@ size_t GetMaximumParametersNumber(
 
 }  // namespace
 
-ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::FunctionCallNode& function) {
+bool ExpressionValidator::ValidateObjectVariableOrVariableOrProperty(
+    const gd::IdentifierNode& identifier) {
+  auto validateVariableTypeForExpression =
+      [this, &identifier](gd::Variable::Type type) {
+        // Collections type can't be used directly in expressions, a child
+        // must be accessed.
+        if (type == Variable::Structure) {
+          RaiseTypeError(_("You need to specify the name of the child variable "
+                           "to access. For example: `MyVariable.child`."),
+                         identifier.identifierNameLocation);
+        } else if (type == Variable::Array) {
+          RaiseTypeError(_("You need to specify the name of the child variable "
+                           "to access. For example: `MyVariable[0]`."),
+                         identifier.identifierNameLocation);
 
+        } else {
+          // Number, string or boolean variables can be used in expressions.
+          return;
+        }
+      };
+
+  const auto& variablesContainersList = projectScopedContainers.GetVariablesContainersList();
+  const auto& objectsContainersList = projectScopedContainers.GetObjectsContainersList();
+  const auto& propertiesContainersList = projectScopedContainers.GetPropertiesContainersList();
+  const auto& parametersVectorsList = projectScopedContainers.GetParametersVectorsList();
+
+  // Unless we find something precise (like a variable or property or parameter with a known type),
+  // we consider this node will be of the type required by the parent.
+  childType = parentType;
+
+  return projectScopedContainers.MatchIdentifierWithName<bool>(identifier.identifierName,
+    [&]() {
+      // This represents an object.
+      if (identifier.childIdentifierName.empty()) {
+        RaiseTypeError(_("An object variable or expression should be entered."),
+                        identifier.identifierNameLocation);
+
+        return true; // We should have found a variable.
+      }
+
+      auto variableExistence = objectsContainersList.HasObjectOrGroupWithVariableNamed(identifier.identifierName, identifier.childIdentifierName);
+
+      if (variableExistence == gd::ObjectsContainersList::DoesNotExist) {
+        RaiseTypeError(_("This variable does not exist on this object or group."),
+                        identifier.childIdentifierNameLocation);
+
+        return true; // We should have found a variable.
+      }
+      else if (variableExistence == gd::ObjectsContainersList::ExistsOnlyOnSomeObjectsOfTheGroup) {
+        RaiseTypeError(_("This variable only exists on some objects of the group. It must be declared for all objects."),
+                        identifier.childIdentifierNameLocation);
+
+        return true; // We should have found a variable.
+      }
+      else if (variableExistence == gd::ObjectsContainersList::GroupIsEmpty) {
+        RaiseTypeError(_("This group is empty. Add an object to this group first."),
+                        identifier.identifierNameLocation);
+
+        return true; // We should have found a variable.
+      }
+
+      auto variableType = objectsContainersList.GetTypeOfObjectOrGroupVariable(identifier.identifierName, identifier.childIdentifierName);
+      ReadChildTypeFromVariable(variableType);
+
+      return true; // We found a variable.
+    }, [&]() {
+      // This is a variable.
+
+      // Try to identify a declared variable with the name (and maybe the child
+      // variable).
+      const gd::Variable& variable =
+          variablesContainersList.Get(identifier.identifierName);
+
+      if (identifier.childIdentifierName.empty()) {
+        // Just the root variable is accessed, check it can be used in an
+        // expression.
+        validateVariableTypeForExpression(variable.GetType());
+        ReadChildTypeFromVariable(variable.GetType());
+
+        return true; // We found a variable.
+      } else {
+        // A child variable is accessed, check it can be used in an expression.
+        if (!variable.HasChild(identifier.childIdentifierName)) {
+          RaiseTypeError(_("No child variable with this name found."),
+                        identifier.childIdentifierNameLocation);
+
+          return true; // We should have found a variable.
+        }
+
+        const gd::Variable& childVariable =
+            variable.GetChild(identifier.childIdentifierName);
+        ReadChildTypeFromVariable(childVariable.GetType());
+        return true; // We found a variable.
+      }
+    }, [&]() {
+      // This is a property.
+      if (!identifier.childIdentifierName.empty()) {
+        RaiseTypeError(_("Accessing a child variable of a property is not possible - just write the property name."),
+            identifier.childIdentifierNameLocation);
+
+        return true; // We found a property, even if the child is not allowed.
+      }
+
+      const gd::NamedPropertyDescriptor& property = projectScopedContainers
+          .GetPropertiesContainersList().Get(identifier.identifierName).second;
+
+      if (property.GetType() == "Number") {
+       childType = Type::Number;
+      } else if (property.GetType() == "Boolean") {
+        // Nothing - we don't know the precise type (this could be used a string or as a number)
+      } else {
+        // Assume type is String or equivalent.
+        childType = Type::String;
+      }
+
+      return true; // We found a property.
+    }, [&]() {
+      // This is a parameter.
+      if (!identifier.childIdentifierName.empty()) {
+        RaiseTypeError(_("Accessing a child variable of a parameter is not possible - just write the parameter name."),
+            identifier.childIdentifierNameLocation);
+
+        return true; // We found a parameter, even if the child is not allowed.
+      }
+
+      const auto& parameter = gd::ParameterMetadataTools::Get(parametersVectorsList, identifier.identifierName);
+      const auto& valueTypeMetadata = parameter.GetValueTypeMetadata();
+      if (valueTypeMetadata.IsNumber()) {
+        childType = Type::Number;
+      } else if (valueTypeMetadata.IsString()) {
+        childType = Type::String;
+      } else if (valueTypeMetadata.IsBoolean()) {
+        // Nothing - we don't know the precise type (this could be used as a string or as a number).
+      } else {
+        RaiseTypeError(_("This parameter is not a string, number or boolean - it can't be used in an expression."),
+            identifier.identifierNameLocation);
+
+        return true; // We found a parameter, even though the type is incompatible.
+      }
+
+      return true; // We found a parameter.
+    }, [&]() {
+      // This is something else.
+      return false;
+    });
+}
+
+ExpressionValidator::Type ExpressionValidator::ValidateFunction(
+    const gd::FunctionCallNode& function) {
   ReportAnyError(function);
-  
-  gd::String objectType = function.objectName.empty() ? "" :
-      GetTypeOfObject(globalObjectsContainer, objectsContainer, function.objectName);
-      
-  gd::String behaviorType = function.behaviorName.empty() ? "" :
-      GetTypeOfBehavior(globalObjectsContainer, objectsContainer, function.behaviorName);
 
-  const gd::ExpressionMetadata &metadata = function.behaviorName.empty() ?
-      function.objectName.empty() ?
-          MetadataProvider::GetAnyExpressionMetadata(platform, function.functionName) :
-          MetadataProvider::GetObjectAnyExpressionMetadata(
-              platform, objectType, function.functionName) : 
-      MetadataProvider::GetBehaviorAnyExpressionMetadata(
-            platform, behaviorType, function.functionName);
+  auto& objectsContainersList = projectScopedContainers.GetObjectsContainersList();
+
+  gd::String objectType =
+      function.objectName.empty()
+          ? ""
+          : objectsContainersList.GetTypeOfObject(function.objectName);
+
+  gd::String behaviorType = function.behaviorName.empty()
+                                ? ""
+                                : objectsContainersList.GetTypeOfBehavior(function.behaviorName);
+
+  const gd::ExpressionMetadata& metadata =
+      function.behaviorName.empty()
+          ? function.objectName.empty()
+                ? MetadataProvider::GetAnyExpressionMetadata(
+                      platform, function.functionName)
+                : MetadataProvider::GetObjectAnyExpressionMetadata(
+                      platform, objectType, function.functionName)
+          : MetadataProvider::GetBehaviorAnyExpressionMetadata(
+                platform, behaviorType, function.functionName);
 
   Type returnType = StringToType(metadata.GetReturnType());
 
   if (!function.objectName.empty() &&
-      !globalObjectsContainer.HasObjectNamed(function.objectName) &&
-      !globalObjectsContainer.GetObjectGroups().Has(function.objectName) &&
-      !objectsContainer.HasObjectNamed(function.objectName) &&
-      !objectsContainer.GetObjectGroups().Has(function.objectName)) {
+      !objectsContainersList.HasObjectOrGroupNamed(function.objectName)) {
     RaiseTypeError(_("This object doesn't exist."),
-                   function.objectNameLocation, /*isFatal=*/false);
+                   function.objectNameLocation,
+                   /*isFatal=*/false);
     return returnType;
   }
 
   if (!function.behaviorName.empty() &&
-      !gd::HasBehaviorInObjectOrGroup(globalObjectsContainer, objectsContainer,
-                                     function.objectName,
-                                     function.behaviorName)) {
+      !objectsContainersList.HasBehaviorInObjectOrGroup(function.objectName,
+                                      function.behaviorName)) {
     RaiseTypeError(_("This behavior is not attached to this object."),
-                   function.behaviorNameLocation, /*isFatal=*/false);
+                   function.behaviorNameLocation,
+                   /*isFatal=*/false);
     return returnType;
   }
 
   if (!function.objectName.empty() &&
-    // If the function needs a capability on the object that may not be covered
-    // by all objects, check it now.
-  !metadata.GetRequiredBaseObjectCapability().empty()) {
-    const gd::ObjectMetadata &objectMetadata =
+      // If the function needs a capability on the object that may not be
+      // covered by all objects, check it now.
+      !metadata.GetRequiredBaseObjectCapability().empty()) {
+    const gd::ObjectMetadata& objectMetadata =
         MetadataProvider::GetObjectMetadata(platform, objectType);
   }
 
   if (gd::MetadataProvider::IsBadExpressionMetadata(metadata)) {
-    RaiseError(
-        "invalid_function_name",
-        _("Cannot find an expression with this name: ") +
-            function.functionName + "\n" +
-            _("Double check that you've not made any typo in the name."),
-        function.location);
-      return returnType;
+    RaiseError("invalid_function_name",
+               _("Cannot find an expression with this name: ") +
+                   function.functionName + "\n" +
+                   _("Double check that you've not made any typo in the name."),
+               function.location);
+    return returnType;
   }
 
   // Validate the type of the function
@@ -128,9 +283,9 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
     } else if (parentType != Type::Number &&
                parentType != Type::NumberOrString) {
       RaiseTypeError(_("You tried to use an expression that returns a "
-                              "number, but another type is expected:") +
-                              " " + TypeToString(parentType),
-                            function.location);
+                       "number, but another type is expected:") +
+                         " " + TypeToString(parentType),
+                     function.location);
       return returnType;
     }
   } else if (returnType == Type::String) {
@@ -144,16 +299,16 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
     } else if (parentType != Type::String &&
                parentType != Type::NumberOrString) {
       RaiseTypeError(_("You tried to use an expression that returns a "
-                              "string, but another type is expected:") +
-                              " " + TypeToString(parentType),
-                            function.location);
+                       "string, but another type is expected:") +
+                         " " + TypeToString(parentType),
+                     function.location);
       return returnType;
     }
   } else {
     if (parentType != returnType) {
       RaiseTypeError(
-          _("You tried to use an expression with the wrong return type:") + " " +
-            TypeToString(returnType),
+          _("You tried to use an expression with the wrong return type:") +
+              " " + TypeToString(returnType),
           function.location);
       return returnType;
     }
@@ -162,10 +317,12 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
   // Validate parameters count
   size_t minParametersCount = GetMinimumParametersNumber(
       metadata.parameters,
-      ExpressionParser2::WrittenParametersFirstIndex(function.objectName, function.behaviorName));
+      ExpressionParser2::WrittenParametersFirstIndex(function.objectName,
+                                                     function.behaviorName));
   size_t maxParametersCount = GetMaximumParametersNumber(
       metadata.parameters,
-      ExpressionParser2::WrittenParametersFirstIndex(function.objectName, function.behaviorName));
+      ExpressionParser2::WrittenParametersFirstIndex(function.objectName,
+                                                     function.behaviorName));
   if (function.parameters.size() < minParametersCount ||
       function.parameters.size() > maxParametersCount) {
     gd::String expectedCountMessage =
@@ -179,28 +336,29 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
     if (function.parameters.size() < minParametersCount) {
       RaiseError(
           "too_few_parameters",
-          _("You have not entered enough parameters for the expression.") + " " +
-              expectedCountMessage,
+          _("You have not entered enough parameters for the expression.") +
+              " " + expectedCountMessage,
           function.location);
     } else {
       RaiseError(
           "extra_parameter",
           _("This parameter was not expected by this expression. Remove it "
-          "or verify that you've entered the proper expression name.") + " " +
-              expectedCountMessage,
-          ExpressionParserLocation(
-              function.parameters[maxParametersCount]->location.GetStartPosition(),
-              function.location.GetEndPosition() - 1));
+            "or verify that you've entered the proper expression name.") +
+              " " + expectedCountMessage,
+          ExpressionParserLocation(function.parameters[maxParametersCount]
+                                       ->location.GetStartPosition(),
+                                   function.location.GetEndPosition() - 1));
     }
     return returnType;
   }
 
   // TODO: reverse the order of diagnostic?
   size_t writtenParametersFirstIndex =
-      ExpressionParser2::WrittenParametersFirstIndex(
-          function.objectName, function.behaviorName);
+      ExpressionParser2::WrittenParametersFirstIndex(function.objectName,
+                                                     function.behaviorName);
   int metadataIndex = writtenParametersFirstIndex;
-  for (int parameterIndex = 0; parameterIndex < function.parameters.size(); parameterIndex++) {
+  for (int parameterIndex = 0; parameterIndex < function.parameters.size();
+       parameterIndex++) {
     auto& parameter = function.parameters[parameterIndex];
     while (metadata.GetParameters()[metadataIndex].IsCodeOnly()) {
       // The sizes are already checked above.
@@ -208,45 +366,45 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
     }
     auto& parameterMetadata = metadata.GetParameters()[metadataIndex];
 
-    if (!parameterMetadata.IsOptional() || dynamic_cast<EmptyNode*>(parameter.get()) == nullptr) {
+    if (!parameterMetadata.IsOptional() ||
+        dynamic_cast<EmptyNode*>(parameter.get()) == nullptr) {
       auto currentParentType = parentType;
       parentType = StringToType(parameterMetadata.GetType());
       parameter->Visit(*this);
       parentType = currentParentType;
-      
-      const gd::String &expectedParameterType = parameterMetadata.GetType();
+
+      const gd::String& expectedParameterType = parameterMetadata.GetType();
       if (gd::ParameterMetadata::IsExpression(
-          ExpressionValidator::variableTypeString, expectedParameterType)) {
-        if (dynamic_cast<IdentifierNode *>(parameter.get()) == nullptr
-         && dynamic_cast<VariableNode *>(parameter.get()) == nullptr) {
-          RaiseError(
-                  "malformed_variable_parameter",
-                  _("A variable name was expected but something else was "
-                    "written. Enter just the name of the variable for this "
-                    "parameter."),
-                parameter->location);
+              ExpressionValidator::variableTypeString, expectedParameterType)) {
+        if (dynamic_cast<IdentifierNode*>(parameter.get()) == nullptr &&
+            dynamic_cast<VariableNode*>(parameter.get()) == nullptr) {
+          RaiseError("malformed_variable_parameter",
+                     _("A variable name was expected but something else was "
+                       "written. Enter just the name of the variable for this "
+                       "parameter."),
+                     parameter->location);
         }
       } else if (gd::ParameterMetadata::IsObject(expectedParameterType)) {
-        if (dynamic_cast<IdentifierNode *>(parameter.get()) == nullptr) {
-          RaiseError(
-                  "malformed_object_parameter",
-                  _("An object name was expected but something else was "
-                    "written. Enter just the name of the object for this "
-                    "parameter."),
-                parameter->location);
+        if (dynamic_cast<IdentifierNode*>(parameter.get()) == nullptr) {
+          RaiseError("malformed_object_parameter",
+                     _("An object name was expected but something else was "
+                       "written. Enter just the name of the object for this "
+                       "parameter."),
+                     parameter->location);
         }
       }
       // String and number are already checked in children.
       else if (!gd::ParameterMetadata::IsExpression(
-               ExpressionValidator::numberTypeString, expectedParameterType)
-            && !gd::ParameterMetadata::IsExpression(
-              ExpressionValidator::stringTypeString, expectedParameterType)) {
-        RaiseError(
-                "unknown_parameter_type",
-                _("This function is improperly set up. Reach out to the "
-                  "extension developer or a GDevelop maintainer to fix "
-                  "this issue"),
-                parameter->location);
+                   ExpressionValidator::numberTypeString,
+                   expectedParameterType) &&
+               !gd::ParameterMetadata::IsExpression(
+                   ExpressionValidator::stringTypeString,
+                   expectedParameterType)) {
+        RaiseError("unknown_parameter_type",
+                   _("This function is improperly set up. Reach out to the "
+                     "extension developer or a GDevelop maintainer to fix "
+                     "this issue"),
+                   parameter->location);
       }
     }
     metadataIndex++;
@@ -254,55 +412,60 @@ ExpressionValidator::Type ExpressionValidator::ValidateFunction(const gd::Functi
   return returnType;
 }
 
-  // TODO factorize in a file with an enum and helpers?
-  const gd::String ExpressionValidator::unknownTypeString = "unknown";
-  const gd::String ExpressionValidator::numberTypeString = "number";
-  const gd::String ExpressionValidator::stringTypeString = "string";
-  const gd::String ExpressionValidator::numberOrStringTypeString = "number|string";
-  const gd::String ExpressionValidator::variableTypeString = "variable";
-  const gd::String ExpressionValidator::objectTypeString = "object";
-  const gd::String ExpressionValidator::emptyTypeString = "empty";
+// TODO factorize in a file with an enum and helpers?
+const gd::String ExpressionValidator::unknownTypeString = "unknown";
+const gd::String ExpressionValidator::numberTypeString = "number";
+const gd::String ExpressionValidator::stringTypeString = "string";
+const gd::String ExpressionValidator::numberOrStringTypeString =
+    "number|string";
+const gd::String ExpressionValidator::variableTypeString = "variable";
+const gd::String ExpressionValidator::objectTypeString = "object";
+const gd::String ExpressionValidator::emptyTypeString = "empty";
 
-  const gd::String &ExpressionValidator::TypeToString(Type type) {
-    switch (type) {
-      case Type::Unknown:
+const gd::String& ExpressionValidator::TypeToString(Type type) {
+  switch (type) {
+    case Type::Unknown:
       return unknownTypeString;
-      case Type::Number:
+    case Type::Number:
       return numberTypeString;
-      case Type::String:
+    case Type::String:
       return stringTypeString;
-      case Type::NumberOrString:
+    case Type::NumberOrString:
       return numberOrStringTypeString;
-      case Type::Variable:
+    case Type::Variable:
       return variableTypeString;
-      case Type::Object:
+    case Type::Object:
       return objectTypeString;
-      case Type::Empty:
+    case Type::Empty:
       return emptyTypeString;
-    }
-    return unknownTypeString;
   }
+  return unknownTypeString;
+}
 
-  ExpressionValidator::Type ExpressionValidator::StringToType(const gd::String &type) {
-    if (type == ExpressionValidator::numberTypeString
-     || gd::ParameterMetadata::IsExpression(ExpressionValidator::numberTypeString, type)) {
-      return Type::Number;
-    }
-    if (type == ExpressionValidator::stringTypeString
-     || gd::ParameterMetadata::IsExpression(ExpressionValidator::stringTypeString, type)) {
-      return Type::String;
-    }
-    if (type == ExpressionValidator::numberOrStringTypeString) {
-      return Type::NumberOrString;
-    }
-    if (type == ExpressionValidator::variableTypeString
-     || gd::ParameterMetadata::IsExpression(ExpressionValidator::variableTypeString, type)) {
-      return Type::Variable;
-    }
-    if (type == ExpressionValidator::objectTypeString
-     || gd::ParameterMetadata::IsObject(type)) {
-      return Type::Object;
-    }
-    return Type::Unknown;
+ExpressionValidator::Type ExpressionValidator::StringToType(
+    const gd::String& type) {
+  if (type == ExpressionValidator::numberTypeString ||
+      gd::ParameterMetadata::IsExpression(ExpressionValidator::numberTypeString,
+                                          type)) {
+    return Type::Number;
   }
+  if (type == ExpressionValidator::stringTypeString ||
+      gd::ParameterMetadata::IsExpression(ExpressionValidator::stringTypeString,
+                                          type)) {
+    return Type::String;
+  }
+  if (type == ExpressionValidator::numberOrStringTypeString) {
+    return Type::NumberOrString;
+  }
+  if (type == ExpressionValidator::variableTypeString ||
+      gd::ParameterMetadata::IsExpression(
+          ExpressionValidator::variableTypeString, type)) {
+    return Type::Variable;
+  }
+  if (type == ExpressionValidator::objectTypeString ||
+      gd::ParameterMetadata::IsObject(type)) {
+    return Type::Object;
+  }
+  return Type::Unknown;
+}
 }  // namespace gd

Core/GDCore/IDE/Events/ExpressionValidator.h

@@ -13,13 +13,18 @@
 #include "GDCore/Tools/MakeUnique.h"
 #include "GDCore/Tools/Localization.h"
 #include "GDCore/Extensions/Metadata/ExpressionMetadata.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
+#include "GDCore/Project/VariablesContainersList.h"
 
 namespace gd {
 class Expression;
 class ObjectsContainer;
+class VariablesContainer;
 class Platform;
 class ParameterMetadata;
 class ExpressionMetadata;
+class VariablesContainersList;
+class ProjectScopedContainers;
 }  // namespace gd
 
 namespace gd {
@@ -33,14 +38,13 @@ namespace gd {
 class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
  public:
   ExpressionValidator(const gd::Platform &platform_,
-                      const gd::ObjectsContainer &globalObjectsContainer_,
-                      const gd::ObjectsContainer &objectsContainer_,
+                      const gd::ProjectScopedContainers & projectScopedContainers_,
                       const gd::String &rootType_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         parentType(StringToType(gd::ParameterMetadata::GetExpressionValueType(rootType_))),
-        childType(Type::Unknown) {};
+        childType(Type::Unknown),
+        forbidsUsageOfBracketsBecauseParentIsObject(false) {};
   virtual ~ExpressionValidator(){};
 
   /**
@@ -48,11 +52,10 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
    * any error including non-fatal ones.
    */
   static bool HasNoErrors(const gd::Platform &platform,
-                      const gd::ObjectsContainer &globalObjectsContainer,
-                      const gd::ObjectsContainer &objectsContainer,
+                      const gd::ProjectScopedContainers & projectScopedContainers,
                       const gd::String &rootType,
                       gd::ExpressionNode& node) {
-    gd::ExpressionValidator validator(platform, globalObjectsContainer, objectsContainer, rootType);
+    gd::ExpressionValidator validator(platform, projectScopedContainers, rootType);
     node.Visit(validator);
     return validator.GetAllErrors().empty();
   }
@@ -82,7 +85,7 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
   }
   void OnVisitOperatorNode(OperatorNode& node) override {
     ReportAnyError(node);
-    
+
     node.leftHandSide->Visit(*this);
     const Type leftType = childType;
 
@@ -100,9 +103,9 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
             "example: \"Your name: \" + VariableString(PlayerName).", node.rightHandSide->location);
       }
       else if (node.op != '+') {
-      RaiseOperatorError(
-          _("You've used an operator that is not supported. Only + can be used "
-            "to concatenate texts."),
+        RaiseOperatorError(
+            _("You've used an operator that is not supported. Only + can be used "
+              "to concatenate texts."),
             ExpressionParserLocation(node.leftHandSide->location.GetEndPosition() + 1, node.location.GetEndPosition()));
       }
     } else if (leftType == Type::Object) {
@@ -121,7 +124,11 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
     node.rightHandSide->Visit(*this);
     const Type rightType = childType;
 
-    childType = leftType;
+    // The type is decided by the first operand, unless it can (`number|string`)
+    // or should (`unknown`) be refined, in which case we go for the right
+    // operand (which got visited knowing the type of the first operand, so it's
+    // equal or strictly more precise than the left operand).
+    childType = (leftType == Type::Unknown || leftType == Type::NumberOrString) ? leftType : rightType;
   }
   void OnVisitUnaryOperatorNode(UnaryOperatorNode& node) override {
     ReportAnyError(node);
@@ -185,28 +192,69 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
   }
   void OnVisitVariableNode(VariableNode& node) override {
     ReportAnyError(node);
-    if (node.child) {
-      node.child->Visit(*this);
-    }
-    childType = Type::Variable;
-    if (parentType == Type::String) {
-      RaiseTypeError(_("Variables must be surrounded by VariableString()."),
-                     node.location);
-    } else if (parentType == Type::Number) {
-      RaiseTypeError(_("Variables must be surrounded by Variable()."),
-                     node.location);
-    } else if (parentType == Type::NumberOrString) {
-      RaiseTypeError(
-          _("Variables must be surrounded by Variable() or VariableString()."),
-          node.location);
-    } else if (parentType != Type::Variable) {
+
+    if (parentType == Type::Variable) {
+      childType = Type::Variable;
+
+      if (node.child) {
+        node.child->Visit(*this);
+      }
+    } else if (parentType == Type::String || parentType == Type::Number || parentType == Type::NumberOrString) {
+      // The node represents a variable or an object variable in an expression waiting for its *value* to be returned.
+      childType = parentType;
+
+      const auto& variablesContainersList = projectScopedContainers.GetVariablesContainersList();
+      const auto& objectsContainersList = projectScopedContainers.GetObjectsContainersList();
+      const auto& propertiesContainerList = projectScopedContainers.GetPropertiesContainersList();
+
+      forbidsUsageOfBracketsBecauseParentIsObject = false;
+      projectScopedContainers.MatchIdentifierWithName<void>(node.name,
+        [&]() {
+          // This represents an object.
+
+          // While understood by the parser, it's forbidden to use the bracket notation just after
+          // an object name (`MyObject["MyVariable"]`).
+          forbidsUsageOfBracketsBecauseParentIsObject = true;
+        }, [&]() {
+          // This is a variable.
+        }, [&]() {
+          // This is a property.
+          // Being in this node implies that there is at least a child - which is not supported for properties.
+          RaiseTypeError(_("Accessing a child variable of a property is not possible - just write the property name."),
+              node.location);
+        }, [&]() {
+          // This is a parameter.
+          // Being in this node implies that there is at least a child - which is not supported for parameters.
+          RaiseTypeError(_("Accessing a child variable of a parameter is not possible - just write the parameter name."),
+              node.location);
+        }, [&]() {
+          // This is something else.
+          RaiseTypeError(_("No object, variable or property with this name found."),
+              node.location);
+        });
+
+      if (node.child) {
+        node.child->Visit(*this);
+      }
+
+      forbidsUsageOfBracketsBecauseParentIsObject = false;
+    } else {
       RaiseTypeError(_("You entered a variable, but this type was expected:") +
                          " " + TypeToString(parentType),
                      node.location);
+
+      if (node.child) {
+        node.child->Visit(*this);
+      }
     }
   }
   void OnVisitVariableAccessorNode(VariableAccessorNode& node) override {
     ReportAnyError(node);
+
+    // In the case we accessed an object variable (`MyObject.MyVariable`),
+    // brackets can now be used (`MyObject.MyVariable["MyChildVariable"]` is now valid).
+    forbidsUsageOfBracketsBecauseParentIsObject = false;
+
     if (node.child) {
       node.child->Visit(*this);
     }
@@ -215,6 +263,15 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
       VariableBracketAccessorNode& node) override {
     ReportAnyError(node);
 
+    if (forbidsUsageOfBracketsBecauseParentIsObject) {
+      RaiseError("brackets_not_allowed_for_objects",
+                 _("You can't use the brackets to access an object variable. "
+                   "Use a dot followed by the variable name, like this: "
+                   "`MyObject.MyVariable`."),
+                 node.location);
+    }
+    forbidsUsageOfBracketsBecauseParentIsObject = false;
+
     Type currentParentType = parentType;
     parentType = Type::NumberOrString;
     node.expression->Visit(*this);
@@ -227,27 +284,39 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
   void OnVisitIdentifierNode(IdentifierNode& node) override {
     ReportAnyError(node);
     if (parentType == Type::String) {
-      RaiseTypeError(_("You must wrap your text inside double quotes "
-                            "(example: \"Hello world\")."),
-                          node.location);
+      if (!ValidateObjectVariableOrVariableOrProperty(node)) {
+        // The identifier is not a variable, so either the variable is not properly declared
+        // or it's a text without quotes.
+        RaiseTypeError(_("You must wrap your text inside double quotes "
+                              "(example: \"Hello world\")."),
+                            node.location);
+      }
     }
     else if (parentType == Type::Number) {
-      RaiseTypeError(
-          _("You must enter a number."), node.location);
+      if (!ValidateObjectVariableOrVariableOrProperty(node)) {
+        // The identifier is not a variable, so the variable is not properly declared.
+        RaiseTypeError(
+            _("You must enter a number."), node.location);
+      }
     }
     else if (parentType == Type::NumberOrString) {
-      RaiseTypeError(
-          _("You must enter a number or a text, wrapped inside double quotes "
-            "(example: \"Hello world\")."),
-          node.location);
+      if (!ValidateObjectVariableOrVariableOrProperty(node)) {
+        // The identifier is not a variable, so either the variable is not properly declared
+        // or it's a text without quotes.
+        RaiseTypeError(
+            _("You must enter a number or a text, wrapped inside double quotes (example: \"Hello world\"), or a variable name."),
+            node.location);
+      }
     }
     else if (parentType != Type::Object && parentType != Type::Variable) {
       // It can't happen.
       RaiseTypeError(
           _("You've entered a name, but this type was expected:") + " " + TypeToString(parentType),
           node.location);
+      childType = parentType;
+    } else {
+      childType = parentType;
     }
-    childType = parentType;
   }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {
     ReportAnyError(node);
@@ -278,6 +347,7 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
  private:
   enum Type {Unknown = 0, Number, String, NumberOrString, Variable, Object, Empty};
   Type ValidateFunction(const gd::FunctionCallNode& function);
+  bool ValidateObjectVariableOrVariableOrProperty(const gd::IdentifierNode& identifier);
 
   void ReportAnyError(const ExpressionNode& node, bool isFatal = true) {
     if (node.diagnostic && node.diagnostic->IsError()) {
@@ -291,7 +361,7 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
     }
   }
 
-  void RaiseError(const gd::String &type, 
+  void RaiseError(const gd::String &type,
       const gd::String &message, const ExpressionParserLocation &location, bool isFatal = true) {
     auto diagnostic = gd::make_unique<ExpressionParserError>(
         type, message, location);
@@ -315,6 +385,16 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
     RaiseError("invalid_operator", message, location);
   }
 
+  void ReadChildTypeFromVariable(gd::Variable::Type variableType) {
+    if (variableType == gd::Variable::Number) {
+      childType = Type::Number;
+    } else if (variableType == gd::Variable::String) {
+      childType = Type::String;
+    } else {
+      // Nothing - we don't know the precise type (this could be used as a string or as a number).
+    }
+  }
+
   static Type StringToType(const gd::String &type);
   static const gd::String &TypeToString(Type type);
   static const gd::String unknownTypeString;
@@ -329,11 +409,11 @@ class GD_CORE_API ExpressionValidator : public ExpressionParser2NodeWorker {
   std::vector<ExpressionParserDiagnostic*> fatalErrors;
   std::vector<ExpressionParserDiagnostic*> allErrors;
   std::vector<std::unique_ptr<ExpressionParserDiagnostic>> supplementalErrors;
-  Type childType;
-  Type parentType;
+  Type childType; ///< The type "discovered" down the tree and passed up.
+  Type parentType; ///< The type "required" by the top of the tree.
+  bool forbidsUsageOfBracketsBecauseParentIsObject;
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
 };
 
 }  // namespace gd

Core/GDCore/IDE/Events/ExpressionVariableOwnerFinder.h

@@ -15,6 +15,7 @@
 #include "GDCore/Extensions/Metadata/ObjectMetadata.h"
 #include "GDCore/Extensions/Metadata/ParameterMetadata.h"
 #include "GDCore/Project/Layout.h"  // For GetTypeOfObject and GetTypeOfBehavior
+#include "GDCore/Project/ObjectsContainersList.h"
 #include "GDCore/Tools/Localization.h"
 
 namespace gd {
@@ -31,6 +32,10 @@ namespace gd {
  * \brief Find the object name that should be used as a context of the
  * expression or sub-expression that a given node represents.
  *
+ * This is needed because of the legacy convention where a "objectvar"
+ * parameter represents a variable of the object represented by the previous "object"
+ * parameter.
+ *
  * \see gd::ExpressionParser2
  */
 class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWorker {
@@ -41,12 +46,11 @@ class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWo
    * context of the expression or sub-expression that a given node represents.
    */
   static const gd::String GetObjectName(const gd::Platform &platform,
-                      const gd::ObjectsContainer &globalObjectsContainer,
-                      const gd::ObjectsContainer &objectsContainer,
+                      const gd::ObjectsContainersList &objectsContainersList,
                       const gd::String& rootObjectName,
                       gd::ExpressionNode& node) {
     gd::ExpressionVariableOwnerFinder typeFinder(
-        platform, globalObjectsContainer, objectsContainer, rootObjectName);
+        platform, objectsContainersList, rootObjectName);
     node.Visit(typeFinder);
     return typeFinder.GetObjectName();
   }
@@ -55,12 +59,10 @@ class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWo
 
  protected:
   ExpressionVariableOwnerFinder(const gd::Platform &platform_,
-                       const gd::ObjectsContainer &globalObjectsContainer_,
-                       const gd::ObjectsContainer &objectsContainer_,
+                       const gd::ObjectsContainersList &objectsContainersList_,
                        const gd::String& rootObjectName_)
       : platform(platform_),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        objectsContainersList(objectsContainersList_),
         rootObjectName(rootObjectName_),
         objectName(""),
         variableNode(nullptr) {};
@@ -126,9 +128,8 @@ class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWo
     }
     const gd::ParameterMetadata* parameterMetadata =
         MetadataProvider::GetFunctionCallParameterMetadata(
-            platform, 
-            globalObjectsContainer,
-            objectsContainer,
+            platform,
+            objectsContainersList,
             functionCall,
             parameterIndex);
     if (parameterMetadata == nullptr
@@ -142,9 +143,8 @@ class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWo
     for (int previousIndex = parameterIndex - 1; previousIndex >= 0; previousIndex--) {
       const gd::ParameterMetadata* previousParameterMetadata =
           MetadataProvider::GetFunctionCallParameterMetadata(
-              platform, 
-              globalObjectsContainer,
-              objectsContainer,
+              platform,
+              objectsContainersList,
               functionCall,
               previousIndex);
       if (previousParameterMetadata != nullptr
@@ -162,8 +162,7 @@ class GD_CORE_API ExpressionVariableOwnerFinder : public ExpressionParser2NodeWo
   gd::ExpressionNode *variableNode;
 
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ObjectsContainersList &objectsContainersList;
   const gd::String &rootObjectName;
 };
 

Core/GDCore/IDE/Events/ExpressionsParameterMover.cpp

@@ -31,16 +31,14 @@ namespace gd {
 class GD_CORE_API ExpressionParameterMover
     : public ExpressionParser2NodeWorker {
  public:
-  ExpressionParameterMover(const gd::ObjectsContainer& globalObjectsContainer_,
-                           const gd::ObjectsContainer& objectsContainer_,
+  ExpressionParameterMover(const gd::ProjectScopedContainers& projectScopedContainers_,
                            const gd::String& behaviorType_,
                            const gd::String& objectType_,
                            const gd::String& functionName_,
                            std::size_t oldIndex_,
                            std::size_t newIndex_)
       : hasDoneMoving(false),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         behaviorType(behaviorType_),
         objectType(objectType_),
         functionName(functionName_),
@@ -98,16 +96,16 @@ class GD_CORE_API ExpressionParameterMover
         // This refactor only applies on events object functions
         // and events object functions doesn't exist yet.
         // This is a dead code.
-        const gd::String& thisObjectType = gd::GetTypeOfObject(
-            globalObjectsContainer, objectsContainer, node.objectName);
+        const gd::String& thisObjectType = projectScopedContainers
+            .GetObjectsContainersList().GetTypeOfObject(node.objectName);
         if (thisObjectType == objectType) {
           moveParameter(node.parameters, 1);
           hasDoneMoving = true;
         }
       } else if (!behaviorType.empty() && !node.behaviorName.empty()) {
         // Move parameter of a behavior function
-        const gd::String& thisBehaviorType = gd::GetTypeOfBehavior(
-            globalObjectsContainer, objectsContainer, node.behaviorName);
+        const gd::String& thisBehaviorType = projectScopedContainers
+            .GetObjectsContainersList().GetTypeOfBehavior(node.behaviorName);
         if (thisBehaviorType == behaviorType) {
           moveParameter(node.parameters, 2);
           hasDoneMoving = true;
@@ -126,8 +124,7 @@ class GD_CORE_API ExpressionParameterMover
 
  private:
   bool hasDoneMoving;
-  const gd::ObjectsContainer& globalObjectsContainer;
-  const gd::ObjectsContainer& objectsContainer;
+  const gd::ProjectScopedContainers& projectScopedContainers;
   const gd::String& behaviorType;  // The behavior type of the function which
                                    // must have a parameter moved (optional).
   const gd::String& objectType;    // The object type of the function which
@@ -155,8 +152,7 @@ bool ExpressionsParameterMover::DoVisitInstruction(gd::Instruction& instruction,
 
     auto node = expression.GetRootNode();
     if (node) {
-      ExpressionParameterMover mover(GetGlobalObjectsContainer(),
-                                     GetObjectsContainer(),
+      ExpressionParameterMover mover(GetProjectScopedContainers(),
                                      behaviorType,
                                      objectType,
                                      functionName,

Core/GDCore/IDE/Events/ExpressionsRenamer.cpp

@@ -23,22 +23,20 @@
 namespace gd {
 
 /**
- * \brief Go through the nodes and change the given object name to a new one.
+ * \brief Go through the nodes and change the given function name to a new name.
  *
  * \see gd::ExpressionParser2
  */
 class GD_CORE_API ExpressionFunctionRenamer
     : public ExpressionParser2NodeWorker {
  public:
-  ExpressionFunctionRenamer(const gd::ObjectsContainer& globalObjectsContainer_,
-                            const gd::ObjectsContainer& objectsContainer_,
+  ExpressionFunctionRenamer(const gd::ProjectScopedContainers& projectScopedContainers_,
                             const gd::String& behaviorType_,
                             const gd::String& objectType_,
                             const gd::String& oldFunctionName_,
                             const gd::String& newFunctionName_)
       : hasDoneRenaming(false),
-        globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+        projectScopedContainers(projectScopedContainers_),
         behaviorType(behaviorType_),
         objectType(objectType_),
         oldFunctionName(oldFunctionName_),
@@ -71,16 +69,18 @@ class GD_CORE_API ExpressionFunctionRenamer
     node.expression->Visit(*this);
     if (node.child) node.child->Visit(*this);
   }
-  void OnVisitIdentifierNode(IdentifierNode& node) override {}
+  void OnVisitIdentifierNode(IdentifierNode& node) override {
+    // Nothing to do as this is either a variable, an object variable a property or something else
+    // but not an expression.
+  }
   void OnVisitObjectFunctionNameNode(ObjectFunctionNameNode& node) override {
     if (!node.behaviorFunctionName.empty()) {
       // Behavior function name
       if (!behaviorType.empty() &&
           node.behaviorFunctionName == oldFunctionName) {
-        const gd::String& thisBehaviorType =
-            gd::GetTypeOfBehavior(globalObjectsContainer,
-                                  objectsContainer,
-                                  node.objectFunctionOrBehaviorName);
+        const gd::String& thisBehaviorType = projectScopedContainers
+          .GetObjectsContainersList().GetTypeOfBehavior(
+            node.objectFunctionOrBehaviorName);
         if (thisBehaviorType == behaviorType) {
           node.behaviorFunctionName = newFunctionName;
           hasDoneRenaming = true;
@@ -90,8 +90,8 @@ class GD_CORE_API ExpressionFunctionRenamer
       // Object function name
       if (behaviorType.empty() && !objectType.empty() &&
           node.objectFunctionOrBehaviorName == oldFunctionName) {
-        const gd::String& thisObjectType = gd::GetTypeOfObject(
-            globalObjectsContainer, objectsContainer, node.objectName);
+        const gd::String& thisObjectType = projectScopedContainers
+            .GetObjectsContainersList().GetTypeOfObject(node.objectName);
         if (thisObjectType == objectType) {
           node.objectFunctionOrBehaviorName = newFunctionName;
           hasDoneRenaming = true;
@@ -104,16 +104,16 @@ class GD_CORE_API ExpressionFunctionRenamer
       if (behaviorType.empty() && !objectType.empty() &&
           !node.objectName.empty()) {
         // Replace an object function
-        const gd::String& thisObjectType = gd::GetTypeOfObject(
-            globalObjectsContainer, objectsContainer, node.objectName);
+        const gd::String& thisObjectType = projectScopedContainers
+            .GetObjectsContainersList().GetTypeOfObject(node.objectName);
         if (thisObjectType == objectType) {
           node.functionName = newFunctionName;
           hasDoneRenaming = true;
         }
       } else if (!behaviorType.empty() && !node.behaviorName.empty()) {
         // Replace a behavior function
-        const gd::String& thisBehaviorType = gd::GetTypeOfBehavior(
-            globalObjectsContainer, objectsContainer, node.behaviorName);
+        const gd::String& thisBehaviorType = projectScopedContainers
+            .GetObjectsContainersList().GetTypeOfBehavior(node.behaviorName);
         if (thisBehaviorType == behaviorType) {
           node.functionName = newFunctionName;
           hasDoneRenaming = true;
@@ -132,8 +132,7 @@ class GD_CORE_API ExpressionFunctionRenamer
 
  private:
   bool hasDoneRenaming;
-  const gd::ObjectsContainer& globalObjectsContainer;
-  const gd::ObjectsContainer& objectsContainer;
+  const gd::ProjectScopedContainers& projectScopedContainers;
   const gd::String& behaviorType;  // The behavior type for which the expression
                                    // must be replaced (optional).
   const gd::String& objectType;    // The object type for which the expression
@@ -159,8 +158,7 @@ bool ExpressionsRenamer::DoVisitInstruction(gd::Instruction& instruction,
 
     auto node = expression.GetRootNode();
     if (node) {
-      ExpressionFunctionRenamer renamer(GetGlobalObjectsContainer(),
-                                        GetObjectsContainer(),
+      ExpressionFunctionRenamer renamer(GetProjectScopedContainers(),
                                         behaviorType,
                                         objectType,
                                         oldFunctionName,

Core/GDCore/IDE/Events/ProjectElementRenamer.cpp

@@ -34,13 +34,12 @@ class GD_CORE_API ExpressionIdentifierStringFinder
 public:
   ExpressionIdentifierStringFinder(
       const gd::Platform &platform_,
-      const gd::ObjectsContainer &globalObjectsContainer_,
-      const gd::ObjectsContainer &objectsContainer_,
+      const gd::ProjectScopedContainers& projectScopedContainers_,
       const gd::String &expressionPlainString_,
       const gd::String &parameterType_, const gd::String &objectName_,
       const gd::String &layerName_, const gd::String &oldName_)
-      : platform(platform_), globalObjectsContainer(globalObjectsContainer_),
-        objectsContainer(objectsContainer_),
+      : platform(platform_),
+        projectScopedContainers(projectScopedContainers_),
         expressionPlainString(expressionPlainString_),
         parameterType(parameterType_), objectName(objectName_),
         layerName(layerName_), oldName(oldName_){};
@@ -82,7 +81,7 @@ protected:
   void OnVisitFunctionCallNode(FunctionCallNode &node) override {
     gd::String lastLayerName;
     gd::ParameterMetadataTools::IterateOverParametersWithIndex(
-        platform, globalObjectsContainer, objectsContainer, node,
+        platform, projectScopedContainers.GetObjectsContainersList(), node,
         [&](const gd::ParameterMetadata &parameterMetadata,
             std::unique_ptr<gd::ExpressionNode> &parameterNode,
             size_t parameterIndex, const gd::String &lastObjectName) {
@@ -123,8 +122,7 @@ protected:
 
 private:
   const gd::Platform &platform;
-  const gd::ObjectsContainer &globalObjectsContainer;
-  const gd::ObjectsContainer &objectsContainer;
+  const gd::ProjectScopedContainers &projectScopedContainers;
   /// It's used to extract parameter content.
   const gd::String &expressionPlainString;
   const gd::String &oldName;
@@ -176,7 +174,7 @@ bool ProjectElementRenamer::DoVisitInstruction(gd::Instruction &instruction,
         auto node = parameterValue.GetRootNode();
         if (node) {
           ExpressionIdentifierStringFinder finder(
-              platform, GetGlobalObjectsContainer(), GetObjectsContainer(),
+              platform, GetProjectScopedContainers(),
               parameterValue.GetPlainString(), parameterType, objectName,
               layerName, oldName);
           node->Visit(finder);

Core/GDCore/IDE/Events/UsedExtensionsFinder.cpp

@@ -108,6 +108,33 @@ void UsedExtensionsFinder::OnVisitUnaryOperatorNode(UnaryOperatorNode& node) {
 // Add variable extension and visit sub-expressions on variable nodes
 void UsedExtensionsFinder::OnVisitVariableNode(VariableNode& node) {
   result.GetUsedExtensions().insert("BuiltinVariables");
+
+  auto type = gd::ExpressionTypeFinder::GetType(
+      project.GetCurrentPlatform(), GetProjectScopedContainers(), rootType, node);
+
+  if (gd::ParameterMetadata::IsExpression("variable", type)) {
+    // Nothing to do (this can't reference an object)
+  } else {
+    GetProjectScopedContainers().MatchIdentifierWithName<void>(node.name,
+      [&]() {
+        // This represents an object.
+        auto metadata = gd::MetadataProvider::GetExtensionAndObjectMetadata(
+          project.GetCurrentPlatform(), node.name);
+        result.GetUsedExtensions().insert(metadata.GetExtension().GetName());
+        for (auto &&includeFile : metadata.GetMetadata().includeFiles) {
+          result.GetUsedIncludeFiles().insert(includeFile);
+        }
+      }, [&]() {
+        // This is a variable.
+      }, [&]() {
+        // This is a property.
+      }, [&]() {
+        // This is a parameter.
+      }, [&]() {
+        // This is something else.
+      });
+  }
+
   if (node.child) node.child->Visit(*this);
 };
 
@@ -127,9 +154,10 @@ void UsedExtensionsFinder::OnVisitVariableBracketAccessorNode(
 // Add extensions bound to Objects/Behaviors/Functions
 void UsedExtensionsFinder::OnVisitIdentifierNode(IdentifierNode &node) {
   auto type = gd::ExpressionTypeFinder::GetType(
-      project.GetCurrentPlatform(), GetGlobalObjectsContainer(),
-      GetObjectsContainer(), rootType, node);
-  if (gd::ParameterMetadata::IsObject(type)) {
+      project.GetCurrentPlatform(), GetProjectScopedContainers(), rootType, node);
+  if (gd::ParameterMetadata::IsObject(type) ||
+      GetObjectsContainersList().HasObjectOrGroupNamed(node.identifierName)) {
+    // An object or object variable is used.
     auto metadata = gd::MetadataProvider::GetExtensionAndObjectMetadata(
         project.GetCurrentPlatform(), node.identifierName);
     result.GetUsedExtensions().insert(metadata.GetExtension().GetName());

Core/GDCore/IDE/Project/ArbitraryResourceWorker.cpp

@@ -293,8 +293,8 @@ void ResourceWorkerInObjectsWorker::DoVisitBehavior(gd::Behavior &behavior){
 gd::ResourceWorkerInObjectsWorker
 GetResourceWorkerOnObjects(const gd::Project &project,
                            gd::ArbitraryResourceWorker &worker) {
-  gd::ResourceWorkerInObjectsWorker eventsWorker(project, worker);
-  return eventsWorker;
+  gd::ResourceWorkerInObjectsWorker resourcesWorker(project, worker);
+  return resourcesWorker;
 }
 
 }  // namespace gd

Core/GDCore/IDE/Project/ObjectsUsingResourceCollector.cpp

@@ -0,0 +1,19 @@
+#include "ObjectsUsingResourceCollector.h"
+
+#include "GDCore/Project/Object.h"
+#include "GDCore/Project/Project.h"
+
+namespace gd {
+
+void ObjectsUsingResourceCollector::DoVisitObject(gd::Object& object) {
+  gd::ResourceNameMatcher resourceNameMatcher(resourceName);
+
+  object.GetConfiguration().ExposeResources(resourceNameMatcher);
+  if (resourceNameMatcher.AnyResourceMatches()) {
+    objectNames.push_back(object.GetName());
+  }
+};
+
+ObjectsUsingResourceCollector::~ObjectsUsingResourceCollector() {}
+
+}  // namespace gd

Core/GDCore/IDE/Project/ObjectsUsingResourceCollector.h

@@ -0,0 +1,89 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2016 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+
+#ifndef ProjectObjectsUsingResourceCollector_H
+#define ProjectObjectsUsingResourceCollector_H
+
+#include <vector>
+
+#include "GDCore/IDE/Project/ArbitraryObjectsWorker.h"
+#include "GDCore/IDE/Project/ArbitraryResourceWorker.h"
+#include "GDCore/String.h"
+
+namespace gd {
+class Object;
+}  // namespace gd
+
+namespace gd {
+
+class GD_CORE_API ObjectsUsingResourceCollector
+    : public ArbitraryObjectsWorker {
+ public:
+  ObjectsUsingResourceCollector(const gd::String& resourceName_)
+      : resourceName(resourceName_){};
+  virtual ~ObjectsUsingResourceCollector();
+
+  std::vector<gd::String>& GetObjectNames() { return objectNames; }
+
+ private:
+  void DoVisitObject(gd::Object& object) override;
+
+  std::vector<gd::String> objectNames;
+  gd::String resourceName;
+};
+
+class GD_CORE_API ResourceNameMatcher : public ArbitraryResourceWorker {
+ public:
+  ResourceNameMatcher(const gd::String& resourceName_)
+      : resourceName(resourceName_), matchesResourceName(false){};
+  virtual ~ResourceNameMatcher(){};
+
+  bool AnyResourceMatches() { return matchesResourceName; }
+  void Reset() { matchesResourceName = false; }
+
+ private:
+  virtual void ExposeFile(gd::String& resource) override{
+      /*Don't care, we just read resource names*/
+  };
+  virtual void ExposeImage(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeAudio(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeFont(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeJson(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeTilemap(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeTileset(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeVideo(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeBitmapFont(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+  virtual void ExposeModel3D(gd::String& otherResourceName) override {
+    MatchResourceName(otherResourceName);
+  };
+
+  void MatchResourceName(gd::String& otherResourceName) {
+    if (otherResourceName == resourceName) matchesResourceName = true;
+  }
+
+  gd::String resourceName;
+  bool matchesResourceName;
+};
+
+};  // namespace gd
+
+#endif  // ProjectObjectsUsingResourceCollector_H

Core/GDCore/IDE/ProjectBrowserHelper.cpp

@@ -16,7 +16,9 @@
 #include "GDCore/Project/EventsFunctionsExtension.h"
 #include "GDCore/Project/ExternalEvents.h"
 #include "GDCore/Project/Layout.h"
+#include "GDCore/Project/PropertiesContainer.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
 #include "GDCore/String.h"
 
 namespace gd {
@@ -86,15 +88,17 @@ void ProjectBrowserHelper::ExposeLayoutEvents(
 void ProjectBrowserHelper::ExposeLayoutEvents(
     gd::Project &project, gd::Layout &layout,
     gd::ArbitraryEventsWorkerWithContext &worker) {
+  auto projectScopedContainers =
+    gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout);
 
   // Add layouts events
-  worker.Launch(layout.GetEvents(), project, layout);
+  worker.Launch(layout.GetEvents(), projectScopedContainers);
 
   // Add external events events
   for (std::size_t s = 0; s < project.GetExternalEventsCount(); s++) {
     auto &externalEvents = project.GetExternalEvents(s);
     if (externalEvents.GetAssociatedLayout() == layout.GetName()) {
-      worker.Launch(externalEvents.GetEvents(), project, layout);
+      worker.Launch(externalEvents.GetEvents(), projectScopedContainers);
     }
   }
 }
@@ -108,15 +112,19 @@ void ProjectBrowserHelper::ExposeProjectEvents(
   // Add layouts events
   for (std::size_t s = 0; s < project.GetLayoutsCount(); s++) {
     auto &layout = project.GetLayout(s);
-    worker.Launch(layout.GetEvents(), project, layout);
+    auto projectScopedContainers =
+      gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout);
+    worker.Launch(layout.GetEvents(), projectScopedContainers);
   }
   // Add external events events
   for (std::size_t s = 0; s < project.GetExternalEventsCount(); s++) {
     const auto &externalEvents = project.GetExternalEvents(s);
     const gd::String &associatedLayout = externalEvents.GetAssociatedLayout();
     if (project.HasLayoutNamed(associatedLayout)) {
-      worker.Launch(project.GetExternalEvents(s).GetEvents(), project,
-                    project.GetLayout(associatedLayout));
+      auto &layout = project.GetLayout(associatedLayout);
+      auto projectScopedContainers =
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout);
+      worker.Launch(project.GetExternalEvents(s).GetEvents(), projectScopedContainers);
     }
   }
   // Add events based extensions
@@ -130,9 +138,11 @@ void ProjectBrowserHelper::ExposeProjectEvents(
       gd::EventsFunctionTools::FreeEventsFunctionToObjectsContainer(
           project, eventsFunctionsExtension, *eventsFunction,
           globalObjectsAndGroups, objectsAndGroups);
+      auto projectScopedContainers =
+        gd::ProjectScopedContainers::MakeNewProjectScopedContainersFor(globalObjectsAndGroups, objectsAndGroups);
+      projectScopedContainers.AddParameters(eventsFunction->GetParametersForEvents(eventsFunctionsExtension));
 
-      worker.Launch(eventsFunction->GetEvents(), globalObjectsAndGroups,
-                    objectsAndGroups);
+      worker.Launch(eventsFunction->GetEvents(), projectScopedContainers);
     }
 
     // Add (behavior) events functions
@@ -169,9 +179,13 @@ void ProjectBrowserHelper::ExposeEventsBasedBehaviorEvents(
     gd::EventsFunctionTools::BehaviorEventsFunctionToObjectsContainer(
         project, eventsBasedBehavior, *eventsFunction, globalObjectsAndGroups,
         objectsAndGroups);
+    auto projectScopedContainers =
+      gd::ProjectScopedContainers::MakeNewProjectScopedContainersFor(globalObjectsAndGroups, objectsAndGroups);
+    projectScopedContainers.AddPropertiesContainer(eventsBasedBehavior.GetSharedPropertyDescriptors());
+    projectScopedContainers.AddPropertiesContainer(eventsBasedBehavior.GetPropertyDescriptors());
+    projectScopedContainers.AddParameters(eventsFunction->GetParametersForEvents(eventsBasedBehavior.GetEventsFunctions()));
 
-    worker.Launch(eventsFunction->GetEvents(), globalObjectsAndGroups,
-                  objectsAndGroups);
+    worker.Launch(eventsFunction->GetEvents(), projectScopedContainers);
   }
 }
 
@@ -185,9 +199,12 @@ void ProjectBrowserHelper::ExposeEventsBasedObjectEvents(
     gd::EventsFunctionTools::ObjectEventsFunctionToObjectsContainer(
         project, eventsBasedObject, *eventsFunction, globalObjectsAndGroups,
         objectsAndGroups);
+    auto projectScopedContainers =
+      gd::ProjectScopedContainers::MakeNewProjectScopedContainersFor(globalObjectsAndGroups, objectsAndGroups);
+    projectScopedContainers.AddPropertiesContainer(eventsBasedObject.GetPropertyDescriptors());
+    projectScopedContainers.AddParameters(eventsFunction->GetParametersForEvents(eventsBasedObject.GetEventsFunctions()));
 
-    worker.Launch(eventsFunction->GetEvents(), globalObjectsAndGroups,
-                  objectsAndGroups);
+    worker.Launch(eventsFunction->GetEvents(), projectScopedContainers);
   }
 }
 

Core/GDCore/IDE/WholeProjectRefactorer.cpp

@@ -5,6 +5,8 @@
  */
 #include "WholeProjectRefactorer.h"
 
+#include <unordered_map>
+
 #include "GDCore/Extensions/Metadata/BehaviorMetadata.h"
 #include "GDCore/Extensions/Metadata/MetadataProvider.h"
 #include "GDCore/Extensions/PlatformExtension.h"
@@ -15,6 +17,8 @@
 #include "GDCore/IDE/Events/CustomObjectTypeRenamer.h"
 #include "GDCore/IDE/Events/EventsBehaviorRenamer.h"
 #include "GDCore/IDE/Events/EventsRefactorer.h"
+#include "GDCore/IDE/Events/EventsPropertyReplacer.h"
+#include "GDCore/IDE/Events/EventsVariableReplacer.h"
 #include "GDCore/IDE/Events/ExpressionsParameterMover.h"
 #include "GDCore/IDE/Events/ExpressionsRenamer.h"
 #include "GDCore/IDE/Events/InstructionsParameterMover.h"
@@ -46,6 +50,8 @@
 #include "GDCore/Project/Layout.h"
 #include "GDCore/Project/ObjectGroup.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/ProjectScopedContainers.h"
+#include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/String.h"
 #include "GDCore/Tools/Log.h"
 
@@ -132,6 +138,72 @@ void WholeProjectRefactorer::EnsureObjectEventsFunctionsProperParameters(
   }
 }
 
+VariablesChangeset WholeProjectRefactorer::ComputeChangesetForVariablesContainer(
+    gd::Project &project,
+    const gd::SerializerElement &oldSerializedVariablesContainer,
+    const gd::VariablesContainer &newVariablesContainer) {
+  gd::VariablesChangeset changeset;
+
+  gd::VariablesContainer oldVariablesContainer;
+  oldVariablesContainer.UnserializeFrom(oldSerializedVariablesContainer);
+
+  if (oldVariablesContainer.GetPersistentUuid() !=
+      newVariablesContainer.GetPersistentUuid()) {
+    gd::LogWarning(
+        _("Called ComputeChangesetForVariablesContainer on variables containers "
+          "that are different - they can't be compared."));
+    return changeset;
+  }
+
+  std::unordered_map<gd::String, gd::String> removedUuidAndNames;
+  for (std::size_t i = 0; i < oldVariablesContainer.Count(); ++i) {
+    const auto &variable = oldVariablesContainer.Get(i);
+    const auto &variableName = oldVariablesContainer.GetNameAt(i);
+
+    // All variables are candidate to be removed.
+    removedUuidAndNames[variable.GetPersistentUuid()] = variableName;
+  }
+  for (std::size_t i = 0; i < newVariablesContainer.Count(); ++i) {
+    const auto &variable = newVariablesContainer.Get(i);
+    const auto &variableName = newVariablesContainer.GetNameAt(i);
+
+    auto existingOldVariableUuidAndName =
+        removedUuidAndNames.find(variable.GetPersistentUuid());
+    if (existingOldVariableUuidAndName == removedUuidAndNames.end()) {
+      // This is a new variable.
+    } else {
+      const gd::String &oldName = existingOldVariableUuidAndName->second;
+
+      if (oldName != variableName) {
+        // This is a renamed variable.
+        changeset.oldToNewVariableNames[oldName] = variableName;
+      }
+
+      // Renamed or not, this is not a removed variable.
+      removedUuidAndNames.erase(variable.GetPersistentUuid());
+    }
+  }
+
+  for (const auto &removedUuidAndName : removedUuidAndNames) {
+    changeset.removedVariableNames.insert(removedUuidAndName.second);
+  }
+
+  return changeset;
+}
+
+void WholeProjectRefactorer::ApplyRefactoringForVariablesContainer(
+    gd::Project &project,
+    const gd::VariablesContainer &newVariablesContainer,
+    const gd::VariablesChangeset& changeset) {
+  gd::EventsVariableReplacer eventsVariableReplacer(
+      project.GetCurrentPlatform(),
+      newVariablesContainer,
+      changeset.oldToNewVariableNames,
+      changeset.removedVariableNames);
+  gd::ProjectBrowserHelper::ExposeProjectEvents(project,
+                                                eventsVariableReplacer);
+}
+
 void WholeProjectRefactorer::UpdateExtensionNameInEventsBasedBehavior(
     gd::Project &project,
     const gd::EventsFunctionsExtension &eventsFunctionsExtension,
@@ -671,6 +743,15 @@ void WholeProjectRefactorer::RenameEventsBasedBehaviorProperty(
         EventsBasedBehavior::GetPropertyExpressionName(newPropertyName));
     gd::ProjectBrowserHelper::ExposeProjectEvents(project, expressionRenamer);
 
+    std::unordered_map<gd::String, gd::String> oldToNewPropertyNames = {{oldPropertyName, newPropertyName}};
+    std::unordered_set<gd::String> removedPropertyNames;
+    gd::EventsPropertyReplacer eventsPropertyReplacer(
+      project.GetCurrentPlatform(),
+      properties,
+      oldToNewPropertyNames,
+      removedPropertyNames);
+    gd::ProjectBrowserHelper::ExposeProjectEvents(project, eventsPropertyReplacer);
+
     gd::InstructionsTypeRenamer actionRenamer = gd::InstructionsTypeRenamer(
         project,
         gd::PlatformExtension::GetBehaviorEventsFunctionFullType(
@@ -698,7 +779,7 @@ void WholeProjectRefactorer::RenameEventsBasedBehaviorSharedProperty(
     const gd::EventsFunctionsExtension &eventsFunctionsExtension,
     const gd::EventsBasedBehavior &eventsBasedBehavior,
     const gd::String &oldPropertyName, const gd::String &newPropertyName) {
-  auto &properties = eventsBasedBehavior.GetPropertyDescriptors();
+  auto &properties = eventsBasedBehavior.GetSharedPropertyDescriptors();
   if (!properties.Has(oldPropertyName))
     return;
 
@@ -732,6 +813,15 @@ void WholeProjectRefactorer::RenameEventsBasedBehaviorSharedProperty(
         EventsBasedBehavior::GetSharedPropertyExpressionName(newPropertyName));
     gd::ProjectBrowserHelper::ExposeProjectEvents(project, expressionRenamer);
 
+    std::unordered_map<gd::String, gd::String> oldToNewPropertyNames = {{oldPropertyName, newPropertyName}};
+    std::unordered_set<gd::String> removedPropertyNames;
+    gd::EventsPropertyReplacer eventsPropertyReplacer(
+      project.GetCurrentPlatform(),
+      properties,
+      oldToNewPropertyNames,
+      removedPropertyNames);
+    gd::ProjectBrowserHelper::ExposeProjectEvents(project, eventsPropertyReplacer);
+
     gd::InstructionsTypeRenamer actionRenamer = gd::InstructionsTypeRenamer(
         project,
         gd::PlatformExtension::GetBehaviorEventsFunctionFullType(
@@ -780,6 +870,15 @@ void WholeProjectRefactorer::RenameEventsBasedObjectProperty(
       EventsBasedObject::GetPropertyExpressionName(newPropertyName));
   gd::ProjectBrowserHelper::ExposeProjectEvents(project, expressionRenamer);
 
+  std::unordered_map<gd::String, gd::String> oldToNewPropertyNames = {{oldPropertyName, newPropertyName}};
+  std::unordered_set<gd::String> removedPropertyNames;
+  gd::EventsPropertyReplacer eventsPropertyReplacer(
+    project.GetCurrentPlatform(),
+    properties,
+    oldToNewPropertyNames,
+    removedPropertyNames);
+  gd::ProjectBrowserHelper::ExposeProjectEvents(project, eventsPropertyReplacer);
+
   gd::InstructionsTypeRenamer actionRenamer = gd::InstructionsTypeRenamer(
       project,
       gd::PlatformExtension::GetObjectEventsFunctionFullType(
@@ -1299,10 +1398,12 @@ void WholeProjectRefactorer::DoRenameObject(
 void WholeProjectRefactorer::ObjectOrGroupRemovedInLayout(
     gd::Project &project, gd::Layout &layout, const gd::String &objectName,
     bool isObjectGroup, bool removeEventsAndGroups) {
+  auto projectScopedContainers = gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout);
+
   // Remove object in the current layout
   if (removeEventsAndGroups) {
     gd::EventsRefactorer::RemoveObjectInEvents(project.GetCurrentPlatform(),
-                                               project, layout,
+                                               projectScopedContainers,
                                                layout.GetEvents(), objectName);
   }
   if (!isObjectGroup) { // Object groups can't have instances or be in other
@@ -1321,8 +1422,9 @@ void WholeProjectRefactorer::ObjectOrGroupRemovedInLayout(
     for (auto &externalEventsName :
          GetAssociatedExternalEvents(project, layout.GetName())) {
       auto &externalEvents = project.GetExternalEvents(externalEventsName);
+
       gd::EventsRefactorer::RemoveObjectInEvents(
-          project.GetCurrentPlatform(), project, layout,
+          project.GetCurrentPlatform(), projectScopedContainers,
           externalEvents.GetEvents(), objectName);
     }
   }
@@ -1344,9 +1446,12 @@ void WholeProjectRefactorer::ObjectOrGroupRenamedInLayout(
     const gd::String &newName, bool isObjectGroup) {
   if (oldName == newName || newName.empty() || oldName.empty())
     return;
+
+  auto projectScopedContainers = gd::ProjectScopedContainers::MakeNewProjectScopedContainersForProjectAndLayout(project, layout);
+
   // Rename object in the current layout
   gd::EventsRefactorer::RenameObjectInEvents(
-      project.GetCurrentPlatform(), project, layout, layout.GetEvents(),
+      project.GetCurrentPlatform(), projectScopedContainers, layout.GetEvents(),
       oldName, newName);
 
   if (!isObjectGroup) { // Object groups can't have instances or be in other
@@ -1362,7 +1467,7 @@ void WholeProjectRefactorer::ObjectOrGroupRenamedInLayout(
        GetAssociatedExternalEvents(project, layout.GetName())) {
     auto &externalEvents = project.GetExternalEvents(externalEventsName);
     gd::EventsRefactorer::RenameObjectInEvents(
-        project.GetCurrentPlatform(), project, layout,
+        project.GetCurrentPlatform(), projectScopedContainers,
         externalEvents.GetEvents(), oldName, newName);
   }
 
@@ -1512,10 +1617,13 @@ void WholeProjectRefactorer::ObjectOrGroupRemovedInEventsFunction(
     gd::ObjectsContainer &globalObjectsContainer,
     gd::ObjectsContainer &objectsContainer, const gd::String &objectName,
     bool isObjectGroup, bool removeEventsAndGroups) {
-  // Remove object in the current layout
+  // In theory we should pass a ProjectScopedContainers to this function so it does not have to construct one.
+  // In practice, this is ok because we only deal with objects.
+  auto projectScopedContainers = gd::ProjectScopedContainers::MakeNewProjectScopedContainersFor(globalObjectsContainer, objectsContainer);
+
   if (removeEventsAndGroups) {
     gd::EventsRefactorer::RemoveObjectInEvents(
-        project.GetCurrentPlatform(), globalObjectsContainer, objectsContainer,
+        project.GetCurrentPlatform(), projectScopedContainers,
         eventsFunction.GetEvents(), objectName);
   }
   if (!isObjectGroup) { // Object groups can't be in other groups
@@ -1547,9 +1655,12 @@ void WholeProjectRefactorer::ObjectOrGroupRenamedInEventsFunction(
     gd::ObjectsContainer &globalObjectsContainer,
     gd::ObjectsContainer &objectsContainer, const gd::String &oldName,
     const gd::String &newName, bool isObjectGroup) {
-  // Rename object in the current layout
+  // In theory we should pass a ProjectScopedContainers to this function so it does not have to construct one.
+  // In practice, this is ok because we only deal with objects.
+  auto projectScopedContainers = gd::ProjectScopedContainers::MakeNewProjectScopedContainersFor(globalObjectsContainer, objectsContainer);
+
   gd::EventsRefactorer::RenameObjectInEvents(
-      project.GetCurrentPlatform(), globalObjectsContainer, objectsContainer,
+      project.GetCurrentPlatform(), projectScopedContainers,
       eventsFunction.GetEvents(), oldName, newName);
 
   if (!isObjectGroup) { // Object groups can't be in other groups
@@ -1594,7 +1705,7 @@ void WholeProjectRefactorer::GlobalObjectOrGroupRemoved(
     if (layout.HasObjectNamed(objectName))
       continue;
 
-    ObjectOrGroupRemovedInLayout(project, layout, objectName, isObjectGroup,
+        ObjectOrGroupRemovedInLayout(project, layout, objectName, isObjectGroup,
                                  removeEventsAndGroups);
   }
 }

Core/GDCore/IDE/WholeProjectRefactorer.h

@@ -7,7 +7,9 @@
 
 #include <set>
 #include <unordered_set>
+#include <unordered_map>
 #include <vector>
+#include "GDCore/String.h"
 namespace gd {
 class Platform;
 class Project;
@@ -18,6 +20,7 @@ class String;
 class EventsFunctionsExtension;
 class EventsFunction;
 class ObjectsContainer;
+class VariablesContainer;
 class EventsBasedBehavior;
 class EventsBasedObject;
 class ArbitraryEventsWorker;
@@ -30,10 +33,20 @@ class Behavior;
 class BehaviorMetadata;
 class UnfilledRequiredBehaviorPropertyProblem;
 class ProjectBrowser;
+class SerializerElement;
 }  // namespace gd
 
 namespace gd {
 
+struct VariablesChangeset {
+  std::unordered_set<gd::String> removedVariableNames;
+  std::unordered_map<gd::String, gd::String> oldToNewVariableNames;
+
+  bool HasRemovedVariables() { return !removedVariableNames.empty(); }
+
+  VariablesChangeset& ClearRemovedVariables() { removedVariableNames.clear(); return *this; }
+};
+
 /**
  * \brief Tool functions to do refactoring on the whole project after
  * changes like deletion or renaming of an object.
@@ -45,6 +58,23 @@ namespace gd {
 class GD_CORE_API WholeProjectRefactorer {
  public:
 
+  /**
+   * \brief Compute the changes made on the variables of a variable container.
+   */
+  static VariablesChangeset ComputeChangesetForVariablesContainer(
+    gd::Project &project,
+    const gd::SerializerElement &oldSerializedVariablesContainer,
+    const gd::VariablesContainer &newVariablesContainer);
+
+  /**
+   * \brief Refactor the project according to the changes (renaming or deletion)
+   * made to variables.
+   */
+  static void ApplyRefactoringForVariablesContainer(
+    gd::Project &project,
+    const gd::VariablesContainer &newVariablesContainer,
+    const gd::VariablesChangeset& changeset);
+
   /**
    * \brief Refactor the project **before** an events function extension is
    * renamed.

Core/GDCore/Project/AbstractEventsBasedEntity.cpp

@@ -4,6 +4,7 @@
  * reserved. This project is released under the MIT License.
  */
 #include "AbstractEventsBasedEntity.h"
+
 #include "EventsFunctionsContainer.h"
 #include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/Tools/MakeUnique.h"
@@ -13,7 +14,10 @@ namespace gd {
 AbstractEventsBasedEntity::AbstractEventsBasedEntity(
     const gd::String& _name,
     gd::EventsFunctionsContainer::FunctionOwner functionContainerSource)
-    : name(_name), fullName(""), eventsFunctionsContainer(functionContainerSource) {}
+    : name(_name),
+      fullName(""),
+      eventsFunctionsContainer(functionContainerSource),
+      propertyDescriptors(functionContainerSource) {}
 
 void AbstractEventsBasedEntity::SerializeTo(SerializerElement& element) const {
   element.SetAttribute("description", description);
@@ -27,8 +31,8 @@ void AbstractEventsBasedEntity::SerializeTo(SerializerElement& element) const {
       "propertyDescriptor", element.AddChild("propertyDescriptors"));
 }
 
-void AbstractEventsBasedEntity::UnserializeFrom(gd::Project& project,
-                                          const SerializerElement& element) {
+void AbstractEventsBasedEntity::UnserializeFrom(
+    gd::Project& project, const SerializerElement& element) {
   description = element.GetStringAttribute("description");
   name = element.GetStringAttribute("name");
   fullName = element.GetStringAttribute("fullName");

Core/GDCore/Project/AbstractEventsBasedEntity.h

@@ -8,7 +8,7 @@
 
 #include <vector>
 #include "GDCore/Project/NamedPropertyDescriptor.h"
-#include "GDCore/Tools/SerializableWithNameList.h"
+#include "GDCore/Project/PropertiesContainer.h"
 #include "GDCore/Project/EventsFunctionsContainer.h"
 #include "GDCore/String.h"
 namespace gd {
@@ -98,15 +98,14 @@ class GD_CORE_API AbstractEventsBasedEntity {
   /**
    * \brief Return a reference to the list of the properties.
    */
-  SerializableWithNameList<NamedPropertyDescriptor>& GetPropertyDescriptors() {
+  gd::PropertiesContainer& GetPropertyDescriptors() {
     return propertyDescriptors;
   }
 
   /**
    * \brief Return a const reference to the list of the properties.
    */
-  const SerializableWithNameList<NamedPropertyDescriptor>& GetPropertyDescriptors()
-      const {
+  const gd::PropertiesContainer& GetPropertyDescriptors() const {
     return propertyDescriptors;
   }
 
@@ -150,7 +149,7 @@ class GD_CORE_API AbstractEventsBasedEntity {
   gd::String fullName;
   gd::String description;
   gd::EventsFunctionsContainer eventsFunctionsContainer;
-  SerializableWithNameList<NamedPropertyDescriptor> propertyDescriptors;
+  gd::PropertiesContainer propertyDescriptors;
   gd::String extensionName;
 };
 

Core/GDCore/Project/BehaviorConfigurationContainer.h

@@ -31,10 +31,10 @@ namespace gd {
  */
 class GD_CORE_API BehaviorConfigurationContainer {
  public:
-
-  BehaviorConfigurationContainer(){};
-  BehaviorConfigurationContainer(const gd::String& name_, const gd::String& type_)
-      : name(name_), type(type_){};
+  BehaviorConfigurationContainer() : folded(false){};
+  BehaviorConfigurationContainer(const gd::String& name_,
+                                 const gd::String& type_)
+      : name(name_), type(type_), folded(false){};
   virtual ~BehaviorConfigurationContainer();
   virtual BehaviorConfigurationContainer* Clone() const { return new BehaviorConfigurationContainer(*this); }
 
@@ -61,7 +61,7 @@ class GD_CORE_API BehaviorConfigurationContainer {
   /**
    * \brief Called when the IDE wants to know about the custom properties of the
    * behavior.
-   * 
+   *
    * \return a std::map with properties names as key.
    * \see gd::PropertyDescriptor
    */
@@ -104,6 +104,17 @@ class GD_CORE_API BehaviorConfigurationContainer {
   const gd::SerializerElement& GetContent() const { return content; };
   gd::SerializerElement& GetContent() { return content; };
 
+  /**
+   * \brief Set if the behavior configuration panel should be folded in the UI.
+   */
+  void SetFolded(bool fold = true) { folded = fold; }
+
+  /**
+   * \brief True if the behavior configuration panel should be folded in the UI.
+   */
+  bool IsFolded() const { return folded; }
+
+
 protected:
   /**
    * \brief Called when the IDE wants to know about the custom properties of the
@@ -148,6 +159,7 @@ protected:
                     ///< in the form "ExtensionName::BehaviorTypeName"
 
   gd::SerializerElement content;  // Storage for the behavior properties
+  bool folded;
 };
 
 }  // namespace gd

Core/GDCore/Project/CustomConfigurationHelper.cpp

@@ -8,6 +8,7 @@
 #include "GDCore/IDE/Project/ArbitraryResourceWorker.h"
 #include "GDCore/Project/Behavior.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/PropertiesContainer.h"
 #include "GDCore/Project/PropertyDescriptor.h"
 #include "GDCore/Serialization/Serializer.h"
 #include "GDCore/Serialization/SerializerElement.h"
@@ -17,7 +18,7 @@
 using namespace gd;
 
 void CustomConfigurationHelper::InitializeContent(
-    const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+    const gd::PropertiesContainer &properties,
     gd::SerializerElement &configurationContent) {
   for (auto &&property : properties.GetInternalVector()) {
     auto &element = configurationContent.AddChild(property->GetName());
@@ -35,7 +36,7 @@ void CustomConfigurationHelper::InitializeContent(
 }
 
 std::map<gd::String, gd::PropertyDescriptor> CustomConfigurationHelper::GetProperties(
-    const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+    const gd::PropertiesContainer &properties,
     const gd::SerializerElement &configurationContent) {
   auto behaviorProperties = std::map<gd::String, gd::PropertyDescriptor>();
 
@@ -71,7 +72,7 @@ std::map<gd::String, gd::PropertyDescriptor> CustomConfigurationHelper::GetPrope
 }
 
 bool CustomConfigurationHelper::UpdateProperty(
-    const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+    const gd::PropertiesContainer &properties,
     gd::SerializerElement &configurationContent,
     const gd::String &propertyName,
     const gd::String &newValue) {

Core/GDCore/Project/CustomConfigurationHelper.h

@@ -9,6 +9,7 @@
 #include "GDCore/Project/Behavior.h"
 #include "GDCore/Project/EventsBasedBehavior.h"
 #include "GDCore/Project/Project.h"
+#include "GDCore/Project/PropertiesContainer.h"
 #include "GDCore/Project/PropertyDescriptor.h"
 #include "GDCore/Serialization/Serializer.h"
 #include "GDCore/Serialization/SerializerElement.h"
@@ -25,15 +26,15 @@ public:
   CustomConfigurationHelper() {}
 
   static void InitializeContent(
-      const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+      const gd::PropertiesContainer &properties,
       gd::SerializerElement &behaviorContent);
 
   static std::map<gd::String, gd::PropertyDescriptor> GetProperties(
-      const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+      const gd::PropertiesContainer &properties,
       const gd::SerializerElement &behaviorContent);
 
   static bool UpdateProperty(
-      const gd::SerializableWithNameList<gd::NamedPropertyDescriptor> &properties,
+      const gd::PropertiesContainer &properties,
       gd::SerializerElement &behaviorContent,
       const gd::String &name,
       const gd::String &value);

Core/GDCore/Project/EventsBasedBehavior.cpp

@@ -13,7 +13,8 @@ namespace gd {
 EventsBasedBehavior::EventsBasedBehavior()
     : AbstractEventsBasedEntity(
         "MyBehavior",
-        gd::EventsFunctionsContainer::FunctionOwner::Behavior) {}
+        gd::EventsFunctionsContainer::FunctionOwner::Behavior),
+        sharedPropertyDescriptors(gd::EventsFunctionsContainer::FunctionOwner::Behavior) {}
 
 void EventsBasedBehavior::SerializeTo(SerializerElement& element) const {
   AbstractEventsBasedEntity::SerializeTo(element);

Core/GDCore/Project/EventsBasedBehavior.h

@@ -9,7 +9,7 @@
 #include <vector>
 #include "GDCore/Project/AbstractEventsBasedEntity.h"
 #include "GDCore/Project/NamedPropertyDescriptor.h"
-#include "GDCore/Tools/SerializableWithNameList.h"
+#include "GDCore/Project/PropertiesContainer.h"
 #include "GDCore/Project/EventsFunctionsContainer.h"
 #include "GDCore/String.h"
 namespace gd {
@@ -91,14 +91,14 @@ class GD_CORE_API EventsBasedBehavior: public AbstractEventsBasedEntity {
   /**
    * \brief Return a reference to the list of shared properties.
    */
-  SerializableWithNameList<NamedPropertyDescriptor>& GetSharedPropertyDescriptors() {
+  gd::PropertiesContainer& GetSharedPropertyDescriptors() {
     return sharedPropertyDescriptors;
   }
 
   /**
    * \brief Return a const reference to the list of shared properties.
    */
-  const SerializableWithNameList<NamedPropertyDescriptor>& GetSharedPropertyDescriptors()
+  const gd::PropertiesContainer& GetSharedPropertyDescriptors()
       const {
     return sharedPropertyDescriptors;
   }
@@ -140,7 +140,7 @@ class GD_CORE_API EventsBasedBehavior: public AbstractEventsBasedEntity {
  private:
   gd::String objectType;
   bool isPrivate = false;
-  SerializableWithNameList<NamedPropertyDescriptor> sharedPropertyDescriptors;
+  gd::PropertiesContainer sharedPropertyDescriptors;
 };
 
 }  // namespace gd

Core/GDCore/Project/EventsBasedObject.cpp

@@ -17,7 +17,7 @@ EventsBasedObject::EventsBasedObject()
 }
 
 EventsBasedObject::~EventsBasedObject() {}
-    
+
 EventsBasedObject::EventsBasedObject(const gd::EventsBasedObject &_eventBasedObject)
         : AbstractEventsBasedEntity(_eventBasedObject) {
   // TODO Add a copy constructor in ObjectsContainer.
@@ -30,14 +30,19 @@ void EventsBasedObject::SerializeTo(SerializerElement& element) const {
 
   AbstractEventsBasedEntity::SerializeTo(element);
   SerializeObjectsTo(element.AddChild("objects"));
+  SerializeFoldersTo(element.AddChild("objectsFolderStructure"));
 }
 
 void EventsBasedObject::UnserializeFrom(gd::Project& project,
-                                          const SerializerElement& element) {
+                                        const SerializerElement& element) {
   defaultName = element.GetStringAttribute("defaultName");
 
   AbstractEventsBasedEntity::UnserializeFrom(project, element);
   UnserializeObjectsFrom(project, element.GetChild("objects"));
+  if (element.HasChild("objectsFolderStructure")) {
+    UnserializeFoldersFrom(project, element.GetChild("objectsFolderStructure", 0));
+  }
+  AddMissingObjectsInRootFolder();
 }
 
 }  // namespace gd

Core/GDCore/Project/Layer.cpp

@@ -19,7 +19,7 @@ Layer::Layer()
       isLocked(false),
       isLightingLayer(false),
       followBaseLayerCamera(false),
-      camera3DNearPlaneDistance(0.1),
+      camera3DNearPlaneDistance(3),
       camera3DFarPlaneDistance(10000),
       camera3DFieldOfView(45),
       ambientLightColorR(200),

Core/GDCore/Project/Layer.h

@@ -13,19 +13,75 @@
 
 namespace gd {
 class Effect;
-}
-namespace gd {
 class Camera;
-}
-namespace gd {
 class SerializerElement;
-}
-namespace gd {
 class EffectsContainer;
 }
 
 namespace gd {
 
+/**
+ * \brief A camera is used to render a specific area of a layout.
+ *
+ * \see gd::Layout
+ * \ingroup PlatformDefinition
+ */
+class GD_CORE_API Camera {
+ public:
+  Camera();
+  ~Camera(){};
+
+  /**
+   * \brief Change the viewport, i.e the area of the window where the camera
+   * will be displayed. \note The coordinates must be between 0 and 1.
+   */
+  void SetViewport(float x1_, float y1_, float x2_, float y2_) {
+    x1 = x1_;
+    x2 = x2_;
+    y1 = y1_;
+    y2 = y2_;
+  };
+  void SetViewportX1(float x1_) { x1 = x1_; };
+  void SetViewportY1(float y1_) { y1 = y1_; };
+  void SetViewportX2(float x2_) { x2 = x2_; };
+  void SetViewportY2(float y2_) { y2 = y2_; };
+  float GetViewportX1() const { return x1; };
+  float GetViewportY1() const { return y1; };
+  float GetViewportX2() const { return x2; };
+  float GetViewportY2() const { return y2; };
+
+  /**
+   * \brief Change the size of the rendered area of the scene, in pixels.
+   */
+  void SetSize(float width_, float height_) {
+    width = width_;
+    height = height_;
+  };
+  float GetWidth() const { return width; };
+  float GetHeight() const { return height; };
+
+  void SetUseDefaultSize(bool useDefaultSize = true) {
+    defaultSize = useDefaultSize;
+  };
+  bool UseDefaultSize() const { return defaultSize; }
+
+  void SetUseDefaultViewport(bool useDefaultViewport = true) {
+    defaultViewport = useDefaultViewport;
+  };
+  bool UseDefaultViewport() const { return defaultViewport; }
+
+ private:
+  bool defaultSize;      ///< True if the camera use the default window size
+  bool defaultViewport;  ///< True if the camera use the default viewport size
+
+  float x1;
+  float y1;
+  float x2;
+  float y2;
+  float width;   ///< The width of the rendered area
+  float height;  ///< The height of the rendered area
+};
+
 /**
  * \brief Represents a layer of a layout.
  *
@@ -241,68 +297,6 @@ struct LayerHasName : public std::binary_function<gd::Layer, gd::String, bool> {
   }
 };
 
-/**
- * \brief A camera is used to render a specific area of a layout.
- *
- * \see gd::Layout
- * \ingroup PlatformDefinition
- */
-class GD_CORE_API Camera {
- public:
-  Camera();
-  ~Camera(){};
-
-  /**
-   * \brief Change the viewport, i.e the area of the window where the camera
-   * will be displayed. \note The coordinates must be between 0 and 1.
-   */
-  void SetViewport(float x1_, float y1_, float x2_, float y2_) {
-    x1 = x1_;
-    x2 = x2_;
-    y1 = y1_;
-    y2 = y2_;
-  };
-  void SetViewportX1(float x1_) { x1 = x1_; };
-  void SetViewportY1(float y1_) { y1 = y1_; };
-  void SetViewportX2(float x2_) { x2 = x2_; };
-  void SetViewportY2(float y2_) { y2 = y2_; };
-  float GetViewportX1() const { return x1; };
-  float GetViewportY1() const { return y1; };
-  float GetViewportX2() const { return x2; };
-  float GetViewportY2() const { return y2; };
-
-  /**
-   * \brief Change the size of the rendered area of the scene, in pixels.
-   */
-  void SetSize(float width_, float height_) {
-    width = width_;
-    height = height_;
-  };
-  float GetWidth() const { return width; };
-  float GetHeight() const { return height; };
-
-  void SetUseDefaultSize(bool useDefaultSize = true) {
-    defaultSize = useDefaultSize;
-  };
-  bool UseDefaultSize() const { return defaultSize; }
-
-  void SetUseDefaultViewport(bool useDefaultViewport = true) {
-    defaultViewport = useDefaultViewport;
-  };
-  bool UseDefaultViewport() const { return defaultViewport; }
-
- private:
-  bool defaultSize;      ///< True if the camera use the default window size
-  bool defaultViewport;  ///< True if the camera use the default viewport size
-
-  float x1;
-  float y1;
-  float x2;
-  float y2;
-  float width;   ///< The width of the rendered area
-  float height;  ///< The height of the rendered area
-};
-
 }  // namespace gd
 
 #endif  // GDCORE_LAYER_H

Core/GDCore/Project/Layout.cpp

@@ -294,6 +294,7 @@ void Layout::SerializeTo(SerializerElement& element) const {
   GetVariables().SerializeTo(element.AddChild("variables"));
   GetInitialInstances().SerializeTo(element.AddChild("instances"));
   SerializeObjectsTo(element.AddChild("objects"));
+  SerializeFoldersTo(element.AddChild("objectsFolderStructure"));
   gd::EventsListSerialization::SerializeEventsTo(events,
                                                  element.AddChild("events"));
 
@@ -353,6 +354,11 @@ void Layout::UnserializeFrom(gd::Project& project,
       project, GetEvents(), element.GetChild("events", 0, "Events"));
 
   UnserializeObjectsFrom(project, element.GetChild("objects", 0, "Objets"));
+  if (element.HasChild("objectsFolderStructure")) {
+    UnserializeFoldersFrom(project, element.GetChild("objectsFolderStructure", 0));
+  }
+  AddMissingObjectsInRootFolder();
+
   initialInstances.UnserializeFrom(
       element.GetChild("instances", 0, "Positions"));
   variables.UnserializeFrom(element.GetChild("variables", 0, "Variables"));
@@ -444,13 +450,15 @@ gd::String GD_CORE_API GetTypeOfObject(const gd::ObjectsContainer& project,
                                        bool searchInGroups) {
   gd::String type;
 
-  // Search in objects
+  // Search in objects.
   if (layout.HasObjectNamed(name))
     type = layout.GetObject(name).GetType();
   else if (project.HasObjectNamed(name))
     type = project.GetObject(name).GetType();
 
-  // Search in groups
+  // Search in groups.
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   else if (searchInGroups) {
     for (std::size_t i = 0; i < layout.GetObjectGroups().size(); ++i) {
       if (layout.GetObjectGroups()[i].GetName() == name) {
@@ -523,7 +531,7 @@ std::vector<gd::String> GD_CORE_API GetBehaviorNamesInObjectOrGroup(
     const gd::ObjectsContainer &project, const gd::ObjectsContainer &layout,
     const gd::String &objectOrGroupName, const gd::String &behaviorType,
     bool searchInGroups) {
-  // Search in objects
+  // Search in objects.
   if (layout.HasObjectNamed(objectOrGroupName)) {
     auto &object = layout.GetObject(objectOrGroupName);
     auto behaviorNames = object.GetAllBehaviorNames();
@@ -542,7 +550,9 @@ std::vector<gd::String> GD_CORE_API GetBehaviorNamesInObjectOrGroup(
     return behaviorNames;
   }
 
-  // Search in groups
+  // Search in groups.
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   const gd::ObjectsContainer *container;
   if (layout.GetObjectGroups().Has(objectOrGroupName)) {
     container = &layout;
@@ -554,12 +564,14 @@ std::vector<gd::String> GD_CORE_API GetBehaviorNamesInObjectOrGroup(
   }
   const vector<gd::String> &groupsObjects =
       container->GetObjectGroups().Get(objectOrGroupName).GetAllObjectsNames();
+
   // Empty groups don't contain any behavior.
   if (groupsObjects.empty()) {
     std::vector<gd::String> behaviorNames;
     return behaviorNames;
   }
 
+  // Compute the intersection of the behaviors of all objects.
   auto behaviorNames = GetBehaviorNamesInObjectOrGroup(
       project, layout, groupsObjects[0], behaviorType, false);
   for (size_t i = 1; i < groupsObjects.size(); i++) {
@@ -587,7 +599,7 @@ bool GD_CORE_API HasBehaviorInObjectOrGroup(const gd::ObjectsContainer &project,
                                             const gd::String &objectOrGroupName,
                                             const gd::String &behaviorName,
                                             bool searchInGroups) {
-  // Search in objects
+  // Search in objects.
   if (layout.HasObjectNamed(objectOrGroupName)) {
     return layout.GetObject(objectOrGroupName).HasBehaviorNamed(behaviorName);
   }
@@ -599,7 +611,9 @@ bool GD_CORE_API HasBehaviorInObjectOrGroup(const gd::ObjectsContainer &project,
     return false;
   }
 
-  // Search in groups
+  // Search in groups.
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   const gd::ObjectsContainer *container;
   if (layout.GetObjectGroups().Has(objectOrGroupName)) {
     container = &layout;
@@ -610,10 +624,12 @@ bool GD_CORE_API HasBehaviorInObjectOrGroup(const gd::ObjectsContainer &project,
   }
   const vector<gd::String> &groupsObjects =
       container->GetObjectGroups().Get(objectOrGroupName).GetAllObjectsNames();
+
   // Empty groups don't contain any behavior.
   if (groupsObjects.empty()) {
     return false;
   }
+
   // Check that all objects have the behavior.
   for (auto &&object : groupsObjects) {
     if (!HasBehaviorInObjectOrGroup(project, layout, object, behaviorName,
@@ -629,7 +645,7 @@ bool GD_CORE_API IsDefaultBehavior(const gd::ObjectsContainer& project,
                                          gd::String objectOrGroupName,
                                          gd::String behaviorName,
                                          bool searchInGroups) {
-  // Search in objects
+  // Search in objects.
   if (layout.HasObjectNamed(objectOrGroupName)) {
     auto &object = layout.GetObject(objectOrGroupName);
     return object.HasBehaviorNamed(behaviorName) &&
@@ -645,7 +661,9 @@ bool GD_CORE_API IsDefaultBehavior(const gd::ObjectsContainer& project,
     return false;
   }
 
-  // Search in groups
+  // Search in groups.
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   const gd::ObjectsContainer *container;
   if (layout.GetObjectGroups().Has(objectOrGroupName)) {
     container = &layout;
@@ -656,10 +674,12 @@ bool GD_CORE_API IsDefaultBehavior(const gd::ObjectsContainer& project,
   }
   const vector<gd::String> &groupsObjects =
       container->GetObjectGroups().Get(objectOrGroupName).GetAllObjectsNames();
+
   // Empty groups don't contain any behavior.
   if (groupsObjects.empty()) {
     return false;
   }
+
   // Check that all objects have the same type.
   for (auto &&object : groupsObjects) {
     if (!IsDefaultBehavior(project, layout, object, behaviorName,
@@ -675,7 +695,7 @@ gd::String GD_CORE_API GetTypeOfBehaviorInObjectOrGroup(const gd::ObjectsContain
                                          const gd::String& objectOrGroupName,
                                          const gd::String& behaviorName,
                                          bool searchInGroups) {
-  // Search in objects
+  // Search in objects.
   if (layout.HasObjectNamed(objectOrGroupName)) {
     auto &object = layout.GetObject(objectOrGroupName);
     return object.HasBehaviorNamed(behaviorName) ?
@@ -691,7 +711,9 @@ gd::String GD_CORE_API GetTypeOfBehaviorInObjectOrGroup(const gd::ObjectsContain
     return "";
   }
 
-  // Search in groups
+  // Search in groups.
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   const gd::ObjectsContainer *container;
   if (layout.GetObjectGroups().Has(objectOrGroupName)) {
     container = &layout;
@@ -702,10 +724,12 @@ gd::String GD_CORE_API GetTypeOfBehaviorInObjectOrGroup(const gd::ObjectsContain
   }
   const vector<gd::String> &groupsObjects =
       container->GetObjectGroups().Get(objectOrGroupName).GetAllObjectsNames();
+
   // Empty groups don't contain any behavior.
   if (groupsObjects.empty()) {
     return "";
   }
+
   // Check that all objects have the behavior with the same type.
   auto behaviorType = GetTypeOfBehaviorInObjectOrGroup(
       project, layout, groupsObjects[0], behaviorName, false);
@@ -742,7 +766,7 @@ gd::String GD_CORE_API GetTypeOfBehavior(const gd::ObjectsContainer& project,
 vector<gd::String> GD_CORE_API
 GetBehaviorsOfObject(const gd::ObjectsContainer& project,
                      const gd::ObjectsContainer& layout,
-                     gd::String name,
+                     const gd::String& name,
                      bool searchInGroups) {
   bool behaviorsAlreadyInserted = false;
   vector<gd::String> behaviors;
@@ -767,6 +791,8 @@ GetBehaviorsOfObject(const gd::ObjectsContainer& project,
   }
 
   // Search in groups
+  // Currently, a group is considered as the "intersection" of all of its objects.
+  // Search "groups is the intersection of its objects" in the codebase.
   if (searchInGroups) {
     for (std::size_t i = 0; i < layout.GetObjectGroups().size(); ++i) {
       if (layout.GetObjectGroups()[i].GetName() == name) {

Core/GDCore/Project/Layout.h

@@ -435,6 +435,7 @@ std::vector<gd::String> GetHiddenLayers(const Layout& layout);
  * \note If a group contains only objects of a same type, then the group has
  * this type. Otherwise, it is considered as an object without any specific
  * type.
+ * \deprecated Use gd::ObjectsContainersList::GetTypeOfObject instead.
  *
  * @return Type of the object/group.
  */
@@ -444,6 +445,7 @@ gd::String GD_CORE_API GetTypeOfObject(const ObjectsContainer& game,
                                        bool searchInGroups = true);
 /**
  * \brief Check if an object or all objects of a group has a behavior.
+ * \deprecated Use gd::ObjectsContainersList::HasBehaviorInObjectOrGroup instead.
  */
 bool GD_CORE_API HasBehaviorInObjectOrGroup(const gd::ObjectsContainer &project,
                                             const gd::ObjectsContainer &layout,
@@ -479,6 +481,7 @@ gd::String GD_CORE_API GetTypeOfBehaviorInObjectOrGroup(const gd::ObjectsContain
 /**
  * \brief Get a type from a behavior name
  * @return Type of the behavior.
+ * @deprecated - Use GetTypeOfBehaviorInObjectOrGroup instead.
  */
 gd::String GD_CORE_API GetTypeOfBehavior(const ObjectsContainer& game,
                                          const ObjectsContainer& layout,
@@ -495,7 +498,7 @@ gd::String GD_CORE_API GetTypeOfBehavior(const ObjectsContainer& game,
 std::vector<gd::String> GD_CORE_API
 GetBehaviorsOfObject(const ObjectsContainer& game,
                      const ObjectsContainer& layout,
-                     gd::String objectName,
+                     const gd::String& objectName,
                      bool searchInGroups = true);
 
 }  // namespace gd

Core/GDCore/Project/LoadingScreen.cpp

@@ -5,7 +5,6 @@
  */
 
 #include "LoadingScreen.h"
-
 #include "GDCore/Serialization/SerializerElement.h"
 
 namespace gd {

Core/GDCore/Project/Object.cpp

@@ -15,6 +15,7 @@
 #include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/Project/PropertyDescriptor.h"
 #include "GDCore/Tools/Log.h"
+#include "GDCore/Tools/UUID/UUID.h"
 
 namespace gd {
 
@@ -35,10 +36,10 @@ Object::Object(const gd::String& name_,
     }
 
 void Object::Init(const gd::Object& object) {
+  persistentUuid = object.persistentUuid;
   name = object.name;
   assetStoreId = object.assetStoreId;
   objectVariables = object.objectVariables;
-  tags = object.tags;
   effectsContainer = object.effectsContainer;
 
   behaviors.clear();
@@ -127,10 +128,11 @@ gd::Behavior* Object::AddNewBehavior(const gd::Project& project,
 
 void Object::UnserializeFrom(gd::Project& project,
                              const SerializerElement& element) {
+  persistentUuid = element.GetStringAttribute("persistentUuid");
+
   SetType(element.GetStringAttribute("type"));
   assetStoreId = element.GetStringAttribute("assetStoreId");
   name = element.GetStringAttribute("name", name, "nom");
-  tags = element.GetStringAttribute("tags");
 
   objectVariables.UnserializeFrom(
       element.GetChild("variables", 0, "Variables"));
@@ -197,10 +199,12 @@ void Object::UnserializeFrom(gd::Project& project,
 }
 
 void Object::SerializeTo(SerializerElement& element) const {
+  if (!persistentUuid.empty())
+    element.SetStringAttribute("persistentUuid", persistentUuid);
+
   element.SetAttribute("name", GetName());
   element.SetAttribute("assetStoreId", GetAssetStoreId());
   element.SetAttribute("type", GetType());
-  element.SetAttribute("tags", GetTags());
   objectVariables.SerializeTo(element.AddChild("variables"));
   effectsContainer.SerializeTo(element.AddChild("effects"));
 
@@ -227,4 +231,18 @@ void Object::SerializeTo(SerializerElement& element) const {
   configuration->SerializeTo(element);
 }
 
+Object& Object::ResetPersistentUuid() {
+  persistentUuid = UUID::MakeUuid4();
+  objectVariables.ResetPersistentUuid();
+
+  return *this;
+}
+
+Object& Object::ClearPersistentUuid() {
+  persistentUuid = "";
+  objectVariables.ClearPersistentUuid();
+
+  return *this;
+}
+
 }  // namespace gd

Core/GDCore/Project/Object.h

@@ -120,14 +120,6 @@ class GD_CORE_API Object {
    */
   const gd::String& GetType() const { return configuration->GetType(); }
 
-  /** \brief Change the tags of the object.
-   */
-  void SetTags(const gd::String& tags_) { tags = tags_; }
-
-  /** \brief Return the tags of the object.
-   */
-  const gd::String& GetTags() const { return tags; }
-
   /** \brief Shortcut to check if the object is a 3D object.
    */
   bool Is3DObject() const { return configuration->Is3DObject(); }
@@ -243,6 +235,18 @@ class GD_CORE_API Object {
    * \see DoUnserializeFrom
    */
   void UnserializeFrom(gd::Project& project, const SerializerElement& element);
+
+  /**
+   * \brief Reset the persistent UUID, used to recognize
+   * the same object between serialization.
+   */
+  Object& ResetPersistentUuid();
+
+  /**
+   * \brief Remove the persistent UUID - when the object no
+   * longer need to be recognized between serializations.
+   */
+  Object& ClearPersistentUuid();
   ///@}
 
  protected:
@@ -256,9 +260,10 @@ class GD_CORE_API Object {
                   ///< object.
   gd::VariablesContainer
       objectVariables;  ///< List of the variables of the object
-  gd::String tags;      ///< Comma-separated list of tags
   gd::EffectsContainer
       effectsContainer;  ///< The effects container for the object.
+  mutable gd::String persistentUuid;  ///< A persistent random version 4 UUID,
+                                      ///< useful for computing changesets.
 
   /**
    * Initialize object using another object. Used by copy-ctor and assign-op.

Core/GDCore/Project/ObjectFolderOrObject.cpp

@@ -0,0 +1,248 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2023 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#include "GDCore/Project/ObjectFolderOrObject.h"
+
+#include <memory>
+
+#include "GDCore/Project/Object.h"
+#include "GDCore/Project/ObjectsContainer.h"
+#include "GDCore/Serialization/SerializerElement.h"
+#include "GDCore/Tools/Log.h"
+
+using namespace std;
+
+namespace gd {
+
+ObjectFolderOrObject ObjectFolderOrObject::badObjectFolderOrObject;
+
+ObjectFolderOrObject::ObjectFolderOrObject()
+    : folderName("__NULL"), object(nullptr) {}
+ObjectFolderOrObject::ObjectFolderOrObject(gd::String folderName_,
+                                           ObjectFolderOrObject* parent_)
+    : folderName(folderName_), parent(parent_), object(nullptr) {}
+ObjectFolderOrObject::ObjectFolderOrObject(gd::Object* object_,
+                                           ObjectFolderOrObject* parent_)
+    : object(object_), parent(parent_) {}
+ObjectFolderOrObject::~ObjectFolderOrObject() {}
+
+bool ObjectFolderOrObject::HasObjectNamed(const gd::String& name) {
+  if (IsFolder()) {
+    return std::any_of(
+        children.begin(),
+        children.end(),
+        [&name](
+            std::unique_ptr<gd::ObjectFolderOrObject>& objectFolderOrObject) {
+          return objectFolderOrObject->HasObjectNamed(name);
+        });
+  }
+  if (!object) return false;
+  return object->GetName() == name;
+}
+ObjectFolderOrObject& ObjectFolderOrObject::GetObjectNamed(
+    const gd::String& name) {
+  if (object && object->GetName() == name) {
+    return *this;
+  }
+  if (IsFolder()) {
+    for (std::size_t j = 0; j < children.size(); j++) {
+      ObjectFolderOrObject& foundInChild = children[j]->GetObjectNamed(name);
+      if (&(foundInChild) != &badObjectFolderOrObject) {
+        return foundInChild;
+      }
+    }
+  }
+  return badObjectFolderOrObject;
+}
+
+void ObjectFolderOrObject::SetFolderName(const gd::String& name) {
+  if (!IsFolder()) return;
+  folderName = name;
+}
+
+ObjectFolderOrObject& ObjectFolderOrObject::GetChildAt(std::size_t index) {
+  if (index >= children.size()) return badObjectFolderOrObject;
+  return *children[index];
+}
+const ObjectFolderOrObject& ObjectFolderOrObject::GetChildAt(std::size_t index) const {
+  if (index >= children.size()) return badObjectFolderOrObject;
+  return *children[index];
+}
+ObjectFolderOrObject& ObjectFolderOrObject::GetObjectChild(
+    const gd::String& name) {
+  for (std::size_t j = 0; j < children.size(); j++) {
+    if (!children[j]->IsFolder()) {
+      if (children[j]->GetObject().GetName() == name) return *children[j];
+    };
+  }
+  return badObjectFolderOrObject;
+}
+
+void ObjectFolderOrObject::InsertObject(gd::Object* insertedObject,
+                                        std::size_t position) {
+  auto objectFolderOrObject =
+      gd::make_unique<ObjectFolderOrObject>(insertedObject, this);
+  if (position < children.size()) {
+    children.insert(children.begin() + position,
+                    std::move(objectFolderOrObject));
+  } else {
+    children.push_back(std::move(objectFolderOrObject));
+  }
+}
+
+std::size_t ObjectFolderOrObject::GetChildPosition(
+    const ObjectFolderOrObject& child) const {
+  for (std::size_t j = 0; j < children.size(); j++) {
+    if (children[j].get() == &child) return j;
+  }
+  return gd::String::npos;
+}
+
+ObjectFolderOrObject& ObjectFolderOrObject::InsertNewFolder(
+    const gd::String& newFolderName, std::size_t position) {
+  auto newFolderPtr =
+      gd::make_unique<ObjectFolderOrObject>(newFolderName, this);
+  gd::ObjectFolderOrObject& newFolder = *(*(children.insert(
+      position < children.size() ? children.begin() + position : children.end(),
+      std::move(newFolderPtr))));
+  return newFolder;
+};
+
+void ObjectFolderOrObject::RemoveRecursivelyObjectNamed(
+    const gd::String& name) {
+  if (IsFolder()) {
+    children.erase(
+        std::remove_if(children.begin(),
+                       children.end(),
+                       [&name](std::unique_ptr<gd::ObjectFolderOrObject>&
+                                   objectFolderOrObject) {
+                         return !objectFolderOrObject->IsFolder() &&
+                                objectFolderOrObject->GetObject().GetName() ==
+                                    name;
+                       }),
+        children.end());
+    for (auto& it : children) {
+      it->RemoveRecursivelyObjectNamed(name);
+    }
+  }
+};
+
+bool ObjectFolderOrObject::IsADescendantOf(
+    const ObjectFolderOrObject& otherObjectFolderOrObject) {
+  if (parent == nullptr) return false;
+  if (&(*parent) == &otherObjectFolderOrObject) return true;
+  return parent->IsADescendantOf(otherObjectFolderOrObject);
+}
+
+void ObjectFolderOrObject::MoveChild(std::size_t oldIndex,
+                                     std::size_t newIndex) {
+  if (!IsFolder()) return;
+  if (oldIndex >= children.size() || newIndex >= children.size()) return;
+
+  std::unique_ptr<gd::ObjectFolderOrObject> objectFolderOrObject =
+      std::move(children[oldIndex]);
+  children.erase(children.begin() + oldIndex);
+  children.insert(children.begin() + newIndex, std::move(objectFolderOrObject));
+}
+
+void ObjectFolderOrObject::RemoveFolderChild(
+    const ObjectFolderOrObject& childToRemove) {
+  if (!IsFolder() || !childToRemove.IsFolder() ||
+      childToRemove.GetChildrenCount() > 0) {
+    return;
+  }
+  std::vector<std::unique_ptr<gd::ObjectFolderOrObject>>::iterator it = find_if(
+      children.begin(),
+      children.end(),
+      [&childToRemove](std::unique_ptr<gd::ObjectFolderOrObject>& child) {
+        return child.get() == &childToRemove;
+      });
+  if (it == children.end()) return;
+
+  children.erase(it);
+}
+
+void ObjectFolderOrObject::MoveObjectFolderOrObjectToAnotherFolder(
+    gd::ObjectFolderOrObject& objectFolderOrObject,
+    gd::ObjectFolderOrObject& newParentFolder,
+    std::size_t newPosition) {
+  if (!newParentFolder.IsFolder()) return;
+  if (newParentFolder.IsADescendantOf(objectFolderOrObject)) return;
+
+  std::vector<std::unique_ptr<gd::ObjectFolderOrObject>>::iterator it =
+      find_if(children.begin(),
+              children.end(),
+              [&objectFolderOrObject](std::unique_ptr<gd::ObjectFolderOrObject>&
+                                          childObjectFolderOrObject) {
+                return childObjectFolderOrObject.get() == &objectFolderOrObject;
+              });
+  if (it == children.end()) return;
+
+  std::unique_ptr<gd::ObjectFolderOrObject> objectFolderOrObjectPtr =
+      std::move(*it);
+  children.erase(it);
+
+  objectFolderOrObjectPtr->parent = &newParentFolder;
+  newParentFolder.children.insert(
+      newPosition < newParentFolder.children.size()
+          ? newParentFolder.children.begin() + newPosition
+          : newParentFolder.children.end(),
+      std::move(objectFolderOrObjectPtr));
+}
+
+void ObjectFolderOrObject::SerializeTo(SerializerElement& element) const {
+  if (IsFolder()) {
+    element.SetAttribute("folderName", GetFolderName());
+    if (children.size() > 0) {
+      SerializerElement& childrenElement = element.AddChild("children");
+      childrenElement.ConsiderAsArrayOf("objectFolderOrObject");
+      for (std::size_t j = 0; j < children.size(); j++) {
+        children[j]->SerializeTo(
+            childrenElement.AddChild("objectFolderOrObject"));
+      }
+    }
+  } else {
+    element.SetAttribute("objectName", GetObject().GetName());
+  }
+}
+
+void ObjectFolderOrObject::UnserializeFrom(
+    gd::Project& project,
+    const SerializerElement& element,
+    gd::ObjectsContainer& objectsContainer) {
+  children.clear();
+  gd::String potentialFolderName = element.GetStringAttribute("folderName", "");
+
+  if (!potentialFolderName.empty()) {
+    object = nullptr;
+    folderName = potentialFolderName;
+
+    if (element.HasChild("children")) {
+      const SerializerElement& childrenElements =
+          element.GetChild("children", 0);
+      childrenElements.ConsiderAsArrayOf("objectFolderOrObject");
+      for (std::size_t i = 0; i < childrenElements.GetChildrenCount(); ++i) {
+        std::unique_ptr<ObjectFolderOrObject> childObjectFolderOrObject =
+            make_unique<ObjectFolderOrObject>();
+        childObjectFolderOrObject->UnserializeFrom(
+            project, childrenElements.GetChild(i), objectsContainer);
+        childObjectFolderOrObject->parent = this;
+        children.push_back(std::move(childObjectFolderOrObject));
+      }
+    }
+  } else {
+    folderName = "";
+    gd::String objectName = element.GetStringAttribute("objectName");
+    if (objectsContainer.HasObjectNamed(objectName)) {
+      object = &objectsContainer.GetObject(objectName);
+    } else {
+      gd::LogError("Object with name " + objectName +
+                   " not found in objects container.");
+      object = nullptr;
+    }
+  }
+};
+
+}  // namespace gd

Core/GDCore/Project/ObjectFolderOrObject.h

@@ -0,0 +1,203 @@
+/*
+ * GDevelop Core
+ * Copyright 2008-2023 Florian Rival (Florian.Rival@gmail.com). All rights
+ * reserved. This project is released under the MIT License.
+ */
+#ifndef GDCORE_OBJECTFOLDEROROBJECT_H
+#define GDCORE_OBJECTFOLDEROROBJECT_H
+#include <memory>
+#include <vector>
+
+#include "GDCore/Serialization/SerializerElement.h"
+#include "GDCore/String.h"
+
+namespace gd {
+class Project;
+class Object;
+class SerializerElement;
+class ObjectsContainer;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief Class representing a folder structure in order to organize objects
+ * in folders (to be used with an ObjectsContainer.)
+ *
+ * \see gd::ObjectsContainer
+ */
+class GD_CORE_API ObjectFolderOrObject {
+ public:
+  /**
+   * \brief Default constructor creating an empty instance. Useful for the null
+   * object pattern.
+   */
+  ObjectFolderOrObject();
+  virtual ~ObjectFolderOrObject();
+  /**
+   * \brief Constructor for creating an instance representing a folder.
+   */
+  ObjectFolderOrObject(gd::String folderName_,
+                       ObjectFolderOrObject* parent_ = nullptr);
+  /**
+   * \brief Constructor for creating an instance representing an object.
+   */
+  ObjectFolderOrObject(gd::Object* object_,
+                       ObjectFolderOrObject* parent_ = nullptr);
+
+  /**
+   * \brief Returns the object behind the instance.
+   */
+  gd::Object& GetObject() const { return *object; }
+
+  /**
+   * \brief Returns true if the instance represents a folder.
+   */
+  bool IsFolder() const { return !folderName.empty(); }
+  /**
+   * \brief Returns the name of the folder.
+   */
+  const gd::String& GetFolderName() const { return folderName; }
+
+  /**
+   * \brief Set the folder name. Does nothing if called on an instance not
+   * representing a folder.
+   */
+  void SetFolderName(const gd::String& name);
+
+  /**
+   * \brief Returns true if the instance represents the object with the given
+   * name or if any of the children does (recursive search).
+   */
+  bool HasObjectNamed(const gd::String& name);
+  /**
+   * \brief Returns the child instance holding the object with the given name
+   * (recursive search).
+   */
+  ObjectFolderOrObject& GetObjectNamed(const gd::String& name);
+
+  /**
+   * \brief Returns the number of children. Returns 0 if the instance represents
+   * an object.
+   */
+  std::size_t GetChildrenCount() const {
+    if (IsFolder()) return children.size();
+    return 0;
+  }
+  /**
+   * \brief Returns the child ObjectFolderOrObject at the given index.
+   */
+  ObjectFolderOrObject& GetChildAt(std::size_t index);
+  /**
+   * \brief Returns the child ObjectFolderOrObject at the given index.
+   */
+  const ObjectFolderOrObject& GetChildAt(std::size_t index) const;
+  /**
+   * \brief Returns the child ObjectFolderOrObject that represents the object
+   * with the given name. To use only if sure that the instance holds the object
+   * in its direct children (no recursive search).
+   *
+   * \note The equivalent method to get a folder by its name cannot be
+   * implemented because there is no unicity enforced on the folder name.
+   */
+  ObjectFolderOrObject& GetObjectChild(const gd::String& name);
+
+  /**
+   * \brief Returns the parent of the instance. If the instance has no parent
+   * (root folder), the null object is returned.
+   */
+  ObjectFolderOrObject& GetParent() {
+    if (parent == nullptr) {
+      return badObjectFolderOrObject;
+    }
+    return *parent;
+  };
+
+  /**
+   * \brief Returns true if the instance is a root folder (that's to say it
+   * has no parent).
+   */
+  bool IsRootFolder() { return !object && !parent; }
+
+  /**
+   * \brief Moves a child from a position to a new one.
+   */
+  void MoveChild(std::size_t oldIndex, std::size_t newIndex);
+  /**
+   * \brief Removes the given child from the instance's children. If the given
+   * child contains children of its own, does nothing.
+   */
+  void RemoveFolderChild(const ObjectFolderOrObject& childToRemove);
+  /**
+   * \brief Removes the child representing the object with the given name from
+   * the instance children and recursively does it for every folder children.
+   */
+  void RemoveRecursivelyObjectNamed(const gd::String& name);
+
+  /**
+   * \brief Inserts an instance representing the given object at the given
+   * position.
+   */
+  void InsertObject(gd::Object* insertedObject,
+                    std::size_t position = (size_t)-1);
+  /**
+   * \brief Inserts an instance representing a folder with the given name at the
+   * given position.
+   */
+  ObjectFolderOrObject& InsertNewFolder(const gd::String& newFolderName,
+                                        std::size_t position);
+  /**
+   * \brief Returns true if the instance is a descendant of the given instance
+   * of ObjectFolderOrObject.
+   */
+  bool IsADescendantOf(const ObjectFolderOrObject& otherObjectFolderOrObject);
+
+  /**
+   * \brief Returns the position of the given instance of ObjectFolderOrObject
+   * in the instance's children.
+   */
+  std::size_t GetChildPosition(const ObjectFolderOrObject& child) const;
+  /**
+   * \brief Moves the given child ObjectFolderOrObject to the given folder at
+   * the given position.
+   */
+  void MoveObjectFolderOrObjectToAnotherFolder(
+      gd::ObjectFolderOrObject& objectFolderOrObject,
+      gd::ObjectFolderOrObject& newParentFolder,
+      std::size_t newPosition);
+
+  /** \name Saving and loading
+   * Members functions related to saving and loading the objects of the class.
+   */
+  ///@{
+  /**
+   * \brief Serialize the ObjectFolderOrObject instance.
+   */
+  void SerializeTo(SerializerElement& element) const;
+
+  /**
+   * \brief Unserialize the ObjectFolderOrObject instance.
+   */
+  void UnserializeFrom(gd::Project& project,
+                       const SerializerElement& element,
+                       ObjectsContainer& objectsContainer);
+  ///@}
+
+ private:
+  static gd::ObjectFolderOrObject badObjectFolderOrObject;
+
+  gd::ObjectFolderOrObject*
+      parent;  // nullptr if root folder, points to the parent folder otherwise.
+
+  // Representing an object:
+  gd::Object* object;  // nullptr if folderName is set.
+
+  // or representing a folder:
+  gd::String folderName;  // Empty if object is set.
+  std::vector<std::unique_ptr<ObjectFolderOrObject>>
+      children;  // Folder children.
+};
+
+}  // namespace gd
+
+#endif  // GDCORE_OBJECTFOLDEROROBJECT_H

Core/GDCore/Project/ObjectGroupsContainer.cpp

@@ -162,4 +162,13 @@ void ObjectGroupsContainer::Move(std::size_t oldIndex, std::size_t newIndex) {
   objectGroups.insert(objectGroups.begin() + newIndex, std::move(objectGroup));
 }
 
+void ObjectGroupsContainer::ForEachNameMatchingSearch(
+    const gd::String& search,
+    std::function<void(const gd::String& name)> fn) const {
+  for (const auto& objectGroup : objectGroups) {
+    if (objectGroup->GetName().FindCaseInsensitive(search) != gd::String::npos)
+      fn(objectGroup->GetName());
+  }
+}
+
 }  // namespace gd

Core/GDCore/Project/ObjectGroupsContainer.h

@@ -116,6 +116,11 @@ class GD_CORE_API ObjectGroupsContainer {
    * \brief Clear all groups of the container.
    */
   inline void Clear() { objectGroups.clear(); }
+
+  /**
+   * \brief Call the callback for each group name matching the specified search.
+   */
+  void ForEachNameMatchingSearch(const gd::String& search, std::function<void(const gd::String& name)> fn) const;
   ///@}
 
   /** \name Saving and loading

Core/GDCore/Project/ObjectsContainer.cpp

@@ -9,12 +9,15 @@
 
 #include "GDCore/Extensions/Platform.h"
 #include "GDCore/Project/Object.h"
+#include "GDCore/Project/ObjectFolderOrObject.h"
 #include "GDCore/Project/Project.h"
 #include "GDCore/Serialization/SerializerElement.h"
 
 namespace gd {
 
-ObjectsContainer::ObjectsContainer() {}
+ObjectsContainer::ObjectsContainer() {
+  rootFolder = gd::make_unique<gd::ObjectFolderOrObject>("__ROOT");
+}
 
 ObjectsContainer::~ObjectsContainer() {}
 
@@ -24,6 +27,22 @@ void ObjectsContainer::SerializeObjectsTo(SerializerElement& element) const {
     initialObjects[j]->SerializeTo(element.AddChild("object"));
   }
 }
+void ObjectsContainer::SerializeFoldersTo(SerializerElement& element) const {
+  rootFolder->SerializeTo(element);
+}
+
+void ObjectsContainer::UnserializeFoldersFrom(
+    gd::Project& project, const SerializerElement& element) {
+  rootFolder->UnserializeFrom(project, element, *this);
+}
+
+void ObjectsContainer::AddMissingObjectsInRootFolder() {
+  for (std::size_t i = 0; i < initialObjects.size(); ++i) {
+    if (!rootFolder->HasObjectNamed(initialObjects[i]->GetName())) {
+      rootFolder->InsertObject(&(*initialObjects[i]));
+    }
+  }
+}
 
 void ObjectsContainer::UnserializeObjectsFrom(
     gd::Project& project, const SerializerElement& element) {
@@ -48,17 +67,23 @@ void ObjectsContainer::UnserializeObjectsFrom(
 bool ObjectsContainer::HasObjectNamed(const gd::String& name) const {
   return (find_if(initialObjects.begin(),
                   initialObjects.end(),
-                  bind2nd(gd::ObjectHasName(), name)) != initialObjects.end());
+                  [&](const std::unique_ptr<gd::Object>& object) {
+                    return object->GetName() == name;
+                  }) != initialObjects.end());
 }
 gd::Object& ObjectsContainer::GetObject(const gd::String& name) {
   return *(*find_if(initialObjects.begin(),
                     initialObjects.end(),
-                    bind2nd(gd::ObjectHasName(), name)));
+                    [&](const std::unique_ptr<gd::Object>& object) {
+                      return object->GetName() == name;
+                    }));
 }
 const gd::Object& ObjectsContainer::GetObject(const gd::String& name) const {
   return *(*find_if(initialObjects.begin(),
                     initialObjects.end(),
-                    bind2nd(gd::ObjectHasName(), name)));
+                    [&](const std::unique_ptr<gd::Object>& object) {
+                      return object->GetName() == name;
+                    }));
 }
 gd::Object& ObjectsContainer::GetObject(std::size_t index) {
   return *initialObjects[index];
@@ -84,6 +109,22 @@ gd::Object& ObjectsContainer::InsertNewObject(const gd::Project& project,
                                        : initialObjects.end(),
       project.CreateObject(objectType, name))));
 
+  rootFolder->InsertObject(&newlyCreatedObject);
+
+  return newlyCreatedObject;
+}
+
+gd::Object& ObjectsContainer::InsertNewObjectInFolder(
+    const gd::Project& project,
+    const gd::String& objectType,
+    const gd::String& name,
+    gd::ObjectFolderOrObject& objectFolderOrObject,
+    std::size_t position) {
+  gd::Object& newlyCreatedObject = *(*(initialObjects.insert(
+      initialObjects.end(), project.CreateObject(objectType, name))));
+
+  objectFolderOrObject.InsertObject(&newlyCreatedObject, position);
+
   return newlyCreatedObject;
 }
 
@@ -97,16 +138,6 @@ gd::Object& ObjectsContainer::InsertObject(const gd::Object& object,
   return newlyCreatedObject;
 }
 
-void ObjectsContainer::SwapObjects(std::size_t firstObjectIndex,
-                                   std::size_t secondObjectIndex) {
-  if (firstObjectIndex >= initialObjects.size() ||
-      secondObjectIndex >= initialObjects.size())
-    return;
-
-  std::iter_swap(initialObjects.begin() + firstObjectIndex,
-                 initialObjects.begin() + secondObjectIndex);
-}
-
 void ObjectsContainer::MoveObject(std::size_t oldIndex, std::size_t newIndex) {
   if (oldIndex >= initialObjects.size() || newIndex >= initialObjects.size())
     return;
@@ -120,30 +151,59 @@ void ObjectsContainer::RemoveObject(const gd::String& name) {
   std::vector<std::unique_ptr<gd::Object>>::iterator objectIt =
       find_if(initialObjects.begin(),
               initialObjects.end(),
-              bind2nd(ObjectHasName(), name));
+              [&](const std::unique_ptr<gd::Object>& object) {
+                return object->GetName() == name;
+              });
   if (objectIt == initialObjects.end()) return;
 
+  rootFolder->RemoveRecursivelyObjectNamed(name);
+
   initialObjects.erase(objectIt);
 }
 
-void ObjectsContainer::MoveObjectToAnotherContainer(
-    const gd::String& name,
+void ObjectsContainer::MoveObjectFolderOrObjectToAnotherContainerInFolder(
+    gd::ObjectFolderOrObject& objectFolderOrObject,
     gd::ObjectsContainer& newContainer,
+    gd::ObjectFolderOrObject& newParentFolder,
     std::size_t newPosition) {
-  std::vector<std::unique_ptr<gd::Object>>::iterator objectIt =
-      find_if(initialObjects.begin(),
-              initialObjects.end(),
-              bind2nd(ObjectHasName(), name));
+  if (objectFolderOrObject.IsFolder() || !newParentFolder.IsFolder()) return;
+
+  std::vector<std::unique_ptr<gd::Object>>::iterator objectIt = find_if(
+      initialObjects.begin(),
+      initialObjects.end(),
+      [&objectFolderOrObject](std::unique_ptr<gd::Object>& object) {
+        return object->GetName() == objectFolderOrObject.GetObject().GetName();
+      });
   if (objectIt == initialObjects.end()) return;
 
   std::unique_ptr<gd::Object> object = std::move(*objectIt);
   initialObjects.erase(objectIt);
 
-  newContainer.initialObjects.insert(
-      newPosition < newContainer.initialObjects.size()
-          ? newContainer.initialObjects.begin() + newPosition
-          : newContainer.initialObjects.end(),
-      std::move(object));
+  newContainer.initialObjects.push_back(std::move(object));
+
+  objectFolderOrObject.GetParent().MoveObjectFolderOrObjectToAnotherFolder(
+      objectFolderOrObject, newParentFolder, newPosition);
+}
+
+std::vector<const ObjectFolderOrObject*>
+ObjectsContainer::GetAllObjectFolderOrObjects() const {
+  std::vector<const ObjectFolderOrObject*> results;
+
+  std::function<void(const ObjectFolderOrObject& folder)> addChildrenOfFolder =
+      [&](const ObjectFolderOrObject& folder) {
+        for (size_t i = 0; i < folder.GetChildrenCount(); ++i) {
+          const auto& child = folder.GetChildAt(i);
+          results.push_back(&child);
+
+          if (child.IsFolder()) {
+            addChildrenOfFolder(child);
+          }
+        }
+      };
+
+  addChildrenOfFolder(*rootFolder);
+
+  return results;
 }
 
 }  // namespace gd

Core/GDCore/Project/ObjectsContainer.h

@@ -9,11 +9,12 @@
 #include <vector>
 #include "GDCore/String.h"
 #include "GDCore/Project/ObjectGroupsContainer.h"
+#include "GDCore/Project/ObjectFolderOrObject.h"
 namespace gd {
 class Object;
 class Project;
 class SerializerElement;
-}
+}  // namespace gd
 #undef GetObject  // Disable an annoying macro
 
 namespace gd {
@@ -98,6 +99,19 @@ class GD_CORE_API ObjectsContainer {
                               const gd::String& objectType,
                               const gd::String& name,
                               std::size_t position);
+  /**
+   * \brief Add a new empty object of type \a objectType called \a name in the
+   * given folder at the specified position.<br>
+   *
+   * \note The object is created using the project's current platform.
+   * \return A reference to the object in the list.
+   */
+  gd::Object& InsertNewObjectInFolder(
+      const gd::Project& project,
+      const gd::String& objectType,
+      const gd::String& name,
+      gd::ObjectFolderOrObject& objectFolderOrObject,
+      std::size_t position);
 
   /**
    * \brief Add a new object to the list
@@ -125,18 +139,18 @@ class GD_CORE_API ObjectsContainer {
   void MoveObject(std::size_t oldIndex, std::size_t newIndex);
 
   /**
-   * \brief Swap the position of the specified objects.
-   */
-  void SwapObjects(std::size_t firstObjectIndex, std::size_t secondObjectIndex);
-
-  /**
-   * Move the specified object to another container, removing it from the current one
-   * and adding it to the new one at the specified position.
+   * Move the specified object to another container, removing it from the
+   * current one and adding it to the new one at the specified position in the
+   * given folder.
    *
-   * \note This does not invalidate the references to the object (object is not moved in memory,
-   * as referenced by smart pointers internally).
+   * \note This does not invalidate the references to the object (object is not
+   * moved in memory, as referenced by smart pointers internally).
    */
-  void MoveObjectToAnotherContainer(const gd::String& name, gd::ObjectsContainer & newContainer, std::size_t newPosition);
+  void MoveObjectFolderOrObjectToAnotherContainerInFolder(
+      gd::ObjectFolderOrObject& objectFolderOrObject,
+      gd::ObjectsContainer& newContainer,
+      gd::ObjectFolderOrObject& newParentFolder,
+      std::size_t newPosition);
 
   /**
    * Provide a raw access to the vector containing the objects
@@ -153,20 +167,43 @@ class GD_CORE_API ObjectsContainer {
   }
   ///@}
 
+  /**
+   * Returns a vector containing all object and folders in this container.
+   * Only use this for checking if you hold a valid `ObjectFolderOrObject` -
+   * don't use this for rendering or anything else.
+   */
+  std::vector<const ObjectFolderOrObject*> GetAllObjectFolderOrObjects() const;
+
+  gd::ObjectFolderOrObject& GetRootFolder() {
+      return *rootFolder;
+  }
+
+  void AddMissingObjectsInRootFolder();
+
   /** \name Saving and loading
    * Members functions related to saving and loading the objects of the class.
    */
   ///@{
   /**
-   * \brief Serialize instances container.
+   * \brief Serialize the objects container.
    */
   void SerializeObjectsTo(SerializerElement& element) const;
 
   /**
-   * \brief Unserialize the instances container.
+   * \brief Unserialize the objects container.
    */
   void UnserializeObjectsFrom(gd::Project& project,
                               const SerializerElement& element);
+  /**
+   * \brief Serialize folder structure.
+   */
+  void SerializeFoldersTo(SerializerElement& element) const;
+
+  /**
+   * \brief Unserialize folder structure.
+   */
+  void UnserializeFoldersFrom(gd::Project& project,
+                              const SerializerElement& element);
   ///@}
 
   /** \name Objects groups management
@@ -190,6 +227,9 @@ class GD_CORE_API ObjectsContainer {
   std::vector<std::unique_ptr<gd::Object> >
       initialObjects;  ///< Objects contained.
   gd::ObjectGroupsContainer objectGroups;
+
+ private:
+  std::unique_ptr<gd::ObjectFolderOrObject> rootFolder;
 };
 
 }  // namespace gd

Core/GDCore/Project/ObjectsContainersList.cpp

@@ -0,0 +1,406 @@
+#include "ObjectsContainersList.h"
+
+#include <vector>
+
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Object.h"
+#include "GDCore/Project/ObjectsContainer.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/VariablesContainer.h"
+#include "GDCore/String.h"
+#include "GDCore/Tools/Log.h"
+
+namespace gd {
+
+ObjectsContainersList
+ObjectsContainersList::MakeNewObjectsContainersListForProjectAndLayout(
+    const gd::Project& project, const gd::Layout& layout) {
+  ObjectsContainersList objectsContainersList;
+  objectsContainersList.Add(project);
+  objectsContainersList.Add(layout);
+  return objectsContainersList;
+}
+
+ObjectsContainersList
+ObjectsContainersList::MakeNewObjectsContainersListForContainers(
+    const gd::ObjectsContainer& globalObjectsContainer,
+    const gd::ObjectsContainer& objectsContainer) {
+  ObjectsContainersList objectsContainersList;
+  objectsContainersList.Add(globalObjectsContainer);
+  objectsContainersList.Add(objectsContainer);
+  return objectsContainersList;
+}
+
+bool ObjectsContainersList::HasObjectOrGroupNamed(
+    const gd::String& name) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(name) || (*it)->GetObjectGroups().Has(name))
+      return true;
+  }
+
+  return false;
+}
+
+bool ObjectsContainersList::HasObjectNamed(const gd::String& name) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(name)) return true;
+  }
+
+  return false;
+}
+
+ObjectsContainersList::VariableExistence
+ObjectsContainersList::HasObjectOrGroupWithVariableNamed(
+    const gd::String& objectOrGroupName, const gd::String& variableName) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      const auto& variables =
+          (*it)->GetObject(objectOrGroupName).GetVariables();
+      return variables.Has(variableName) ? VariableExistence::Exists
+                                         : VariableExistence::DoesNotExist;
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // This could be adapted if objects groups have variables in the future.
+
+      // Currently, a group is considered as the "intersection" of all of its
+      // objects. Search "groups is the intersection of its objects" in the
+      // codebase. Consider that a group has a variable if all objects of the
+      // group have it:
+      const auto& objectGroup = (*it)->GetObjectGroups().Get(objectOrGroupName);
+      const auto& objectNames = objectGroup.GetAllObjectsNames();
+      if (objectNames.empty()) return VariableExistence::GroupIsEmpty;
+
+      bool existsOnAtLeastOneObject = false;
+      bool missingOnAtLeastOneObject = false;
+      for (const auto& objectName : objectNames) {
+        if (!HasObjectWithVariableNamed(objectName, variableName)) {
+          missingOnAtLeastOneObject = true;
+          if (existsOnAtLeastOneObject) {
+            return VariableExistence::ExistsOnlyOnSomeObjectsOfTheGroup;
+          }
+        } else {
+          existsOnAtLeastOneObject = true;
+          if (missingOnAtLeastOneObject) {
+            return VariableExistence::ExistsOnlyOnSomeObjectsOfTheGroup;
+          }
+        }
+      }
+
+      if (missingOnAtLeastOneObject) {
+        return VariableExistence::DoesNotExist;
+      }
+
+      return VariableExistence::Exists;
+    }
+  }
+
+  return VariableExistence::DoesNotExist;
+}
+
+bool ObjectsContainersList::HasObjectWithVariableNamed(
+    const gd::String& objectName, const gd::String& variableName) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectName)) {
+      const auto& variables = (*it)->GetObject(objectName).GetVariables();
+      return variables.Has(variableName);
+    }
+  }
+
+  return false;
+}
+
+bool ObjectsContainersList::HasVariablesContainer(
+    const gd::String& objectOrGroupName,
+    const gd::VariablesContainer& variablesContainer) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      return &variablesContainer ==
+             &(*it)->GetObject(objectOrGroupName).GetVariables();
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // Could be adapted if objects groups have variables in the future.
+      // This would allow handling the renaming of variables of an object group.
+    }
+  }
+
+  return false;
+}
+
+const gd::VariablesContainer*
+ObjectsContainersList::GetObjectOrGroupVariablesContainer(
+    const gd::String& objectOrGroupName) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      return &(*it)->GetObject(objectOrGroupName).GetVariables();
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // Could be adapted if objects groups have variables in the future.
+      // This would allow handling the renaming of variables of an object group.
+    }
+  }
+
+  return nullptr;
+}
+
+gd::Variable::Type ObjectsContainersList::GetTypeOfObjectOrGroupVariable(
+    const gd::String& objectOrGroupName, const gd::String& variableName) const {
+
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      const auto& variables =
+          (*it)->GetObject(objectOrGroupName).GetVariables();
+
+      return variables.Get(variableName).GetType();
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // This could be adapted if objects groups have variables in the future.
+
+      // Currently, a group is considered as the "intersection" of all of its
+      // objects. Search "groups is the intersection of its objects" in the
+      // codebase. Consider that the first object having the variable will
+      // define its type.
+      const auto& objectGroup = (*it)->GetObjectGroups().Get(objectOrGroupName);
+      const auto& objectNames = objectGroup.GetAllObjectsNames();
+
+      for (const auto& objectName : objectNames) {
+        if (HasObjectWithVariableNamed(objectName, variableName)) {
+          return GetTypeOfObjectVariable(objectName, variableName);
+        }
+      }
+
+      return Variable::Type::Number;
+    }
+  }
+
+  return Variable::Type::Number;
+}
+
+gd::Variable::Type ObjectsContainersList::GetTypeOfObjectVariable(const gd::String& objectName, const gd::String& variableName) const {
+
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectName)) {
+      const auto& variables =
+          (*it)->GetObject(objectName).GetVariables();
+
+      return variables.Get(variableName).GetType();
+    }
+  }
+
+  return Variable::Type::Number;
+}
+
+void ObjectsContainersList::ForEachObjectOrGroupVariableMatchingSearch(
+    const gd::String& objectOrGroupName,
+    const gd::String& search,
+    std::function<void(const gd::String& variableName,
+                       const gd::Variable& variable)> fn) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      const auto& variables =
+          (*it)->GetObject(objectOrGroupName).GetVariables();
+      variables.ForEachVariableMatchingSearch(search, fn);
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // This could be adapted if objects groups have variables in the future.
+
+      // Currently, a group is considered as the "intersection" of all of its
+      // objects. Search "groups is the intersection of its objects" in the
+      // codebase. Consider that a group has a variable if all objects of the
+      // group have it:
+      const auto& objectGroup = (*it)->GetObjectGroups().Get(objectOrGroupName);
+      const auto& objectNames = objectGroup.GetAllObjectsNames();
+
+      if (objectNames.empty()) return;
+      const auto& firstObjectName = objectNames.front();
+      ForEachObjectVariableMatchingSearch(
+          firstObjectName,
+          search,
+          [&](const gd::String& variableName, const gd::Variable& variable) {
+            for (const auto& objectName : objectGroup.GetAllObjectsNames()) {
+              if (!HasObjectWithVariableNamed(objectName, variableName)) {
+                return;  // This variable is not shared by all objects of the
+                         // group.
+              }
+            }
+
+            // This variable is shared by all objects in the group. Note that
+            // other objects can have it with a different type - we allow this.
+            fn(variableName, variable);
+          });
+    }
+  }
+}
+
+void ObjectsContainersList::ForEachObjectVariableMatchingSearch(
+    const gd::String& objectOrGroupName,
+    const gd::String& search,
+    std::function<void(const gd::String& variableName,
+                       const gd::Variable& variable)> fn) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      const auto& variables =
+          (*it)->GetObject(objectOrGroupName).GetVariables();
+      variables.ForEachVariableMatchingSearch(search, fn);
+    }
+  }
+}
+
+void ObjectsContainersList::ForEachNameMatchingSearch(
+    const gd::String& search,
+    std::function<void(const gd::String& name,
+                       const gd::ObjectConfiguration* objectConfiguration)> fn)
+    const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    for (const auto& object : (*it)->GetObjects()) {
+      if (object->GetName().FindCaseInsensitive(search) != gd::String::npos)
+        fn(object->GetName(), &object->GetConfiguration());
+    }
+    (*it)->GetObjectGroups().ForEachNameMatchingSearch(
+        search, [&](const gd::String& name) { fn(name, nullptr); });
+  }
+}
+
+std::vector<gd::String> ObjectsContainersList::ExpandObjectName(
+    const gd::String& objectOrGroupName,
+    const gd::String& onlyObjectToSelectIfPresent) const {
+  std::vector<gd::String> realObjects;
+
+  // Check progressively each object container to find the object or the group
+  // with the specified name.
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    if ((*it)->HasObjectNamed(objectOrGroupName)) {
+      // We found the object, it's a single object with this name.
+      realObjects.push_back(objectOrGroupName);
+      break;
+    }
+    if ((*it)->GetObjectGroups().Has(objectOrGroupName)) {
+      // We found a group with this name, expand the object names inside of it.
+      realObjects =
+          (*it)->GetObjectGroups().Get(objectOrGroupName).GetAllObjectsNames();
+      break;
+    }
+  }
+
+  // If the "current object" is present, use it and only it.
+  if (!onlyObjectToSelectIfPresent.empty() &&
+      find(realObjects.begin(),
+           realObjects.end(),
+           onlyObjectToSelectIfPresent) != realObjects.end()) {
+    realObjects.clear();
+    realObjects.push_back(onlyObjectToSelectIfPresent);
+  }
+
+  // Ensure that all returned objects actually exists (i.e: if some groups have
+  // names refering to non existing objects, don't return them).
+  for (std::size_t i = 0; i < realObjects.size();) {
+    if (!HasObjectNamed(realObjects[i]))
+      realObjects.erase(realObjects.begin() + i);
+    else
+      ++i;
+  }
+
+  return realObjects;
+}
+
+void ObjectsContainersList::ForEachObject(
+    std::function<void(const gd::Object& object)> fn) const {
+  for (auto it = objectsContainers.rbegin(); it != objectsContainers.rend();
+       ++it) {
+    const auto& objectsContainer = **it;
+    for (const auto& object : objectsContainer.GetObjects()) {
+      fn(*object);
+    }
+  }
+}
+
+gd::String ObjectsContainersList::GetTypeOfObject(
+    const gd::String& objectName) const {
+  if (objectsContainers.size() != 2) {
+    std::cout << this << std::endl;
+    std::cout << objectsContainers.size() << std::endl;
+    // TODO: rework forwarded methods so they can work with any number of
+    // containers.
+    gd::LogFatalError(
+        "ObjectsContainersList::GetTypeOfObject called with objectsContainers "
+        "not being exactly 2. This is a logical error and will crash.");
+  }
+  return gd::GetTypeOfObject(
+      *objectsContainers[0], *objectsContainers[1], objectName, true);
+}
+
+bool ObjectsContainersList::HasBehaviorInObjectOrGroup(
+    const gd::String& objectOrGroupName, const gd::String& behaviorName) const {
+  if (objectsContainers.size() != 2) {
+    // TODO: rework forwarded methods so they can work with any number of
+    // containers.
+    gd::LogFatalError(
+        "ObjectsContainersList::GetTypeOfObject called with objectsContainers "
+        "not being exactly 2. This is a logical error and will crash.");
+  }
+  return gd::HasBehaviorInObjectOrGroup(*objectsContainers[0],
+                                        *objectsContainers[1],
+                                        objectOrGroupName,
+                                        behaviorName,
+                                        true);
+}
+
+gd::String ObjectsContainersList::GetTypeOfBehaviorInObjectOrGroup(
+    const gd::String& objectOrGroupName,
+    const gd::String& behaviorName,
+    bool searchInGroups) const {
+  if (objectsContainers.size() != 2) {
+    // TODO: rework forwarded methods so they can work with any number of
+    // containers.
+    gd::LogFatalError(
+        "ObjectsContainersList::GetTypeOfObject called with objectsContainers "
+        "not being exactly 2. This is a logical error and will crash.");
+  }
+  return gd::GetTypeOfBehaviorInObjectOrGroup(*objectsContainers[0],
+                                              *objectsContainers[1],
+                                              objectOrGroupName,
+                                              behaviorName,
+                                              searchInGroups);
+}
+
+gd::String ObjectsContainersList::GetTypeOfBehavior(
+    const gd::String& behaviorName, bool searchInGroups) const {
+  if (objectsContainers.size() != 2) {
+    // TODO: rework forwarded methods so they can work with any number of
+    // containers.
+    gd::LogFatalError(
+        "ObjectsContainersList::GetTypeOfObject called with objectsContainers "
+        "not being exactly 2. This is a logical error and will crash.");
+  }
+  return gd::GetTypeOfBehavior(*objectsContainers[0],
+                               *objectsContainers[1],
+                               behaviorName,
+                               searchInGroups);
+}
+
+std::vector<gd::String> ObjectsContainersList::GetBehaviorsOfObject(
+    const gd::String& objectName, bool searchInGroups) const {
+  if (objectsContainers.size() != 2) {
+    // TODO: rework forwarded methods so they can work with any number of
+    // containers.
+    gd::LogFatalError(
+        "ObjectsContainersList::GetTypeOfObject called with objectsContainers "
+        "not being exactly 2. This is a logical error and will crash.");
+  }
+
+  return gd::GetBehaviorsOfObject(
+      *objectsContainers[0], *objectsContainers[1], objectName, searchInGroups);
+}
+
+}  // namespace gd

Core/GDCore/Project/ObjectsContainersList.h

@@ -0,0 +1,183 @@
+#pragma once
+#include <vector>
+
+#include "Variable.h"
+
+namespace gd {
+class String;
+class Project;
+class Layout;
+class ObjectsContainer;
+class VariablesContainer;
+class Object;
+class ObjectConfiguration;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief A list of objects containers, useful for accessing objects in a
+ * scoped way, along with methods to access them.
+ *
+ * \see gd::Object
+ * \see gd::ObjectsContainer
+ * \see gd::Project
+ * \see gd::Layout
+ *
+ * \ingroup PlatformDefinition
+ */
+class GD_CORE_API ObjectsContainersList {
+ public:
+  virtual ~ObjectsContainersList(){};
+
+  static ObjectsContainersList MakeNewObjectsContainersListForProjectAndLayout(
+      const gd::Project& project, const gd::Layout& layout);
+
+  static ObjectsContainersList MakeNewObjectsContainersListForContainers(
+      const gd::ObjectsContainer& globalObjectsContainer,
+      const gd::ObjectsContainer& objectsContainer);
+
+  /**
+   * \brief Check if the specified object or group exists.
+   */
+  bool HasObjectOrGroupNamed(const gd::String& name) const;
+
+  enum VariableExistence {
+    DoesNotExist,
+    Exists,
+    GroupIsEmpty,
+    ExistsOnlyOnSomeObjectsOfTheGroup
+  };
+
+  /**
+   * \brief Check if the specified object or group has the specified variable in
+   * its declared variables.
+   */
+  VariableExistence HasObjectOrGroupWithVariableNamed(
+      const gd::String& objectOrGroupName,
+      const gd::String& variableName) const;
+
+  /**
+   * \brief Check if the specified object or group has the specified variables
+   * container.
+   */
+  bool HasVariablesContainer(
+      const gd::String& objectOrGroupName,
+      const gd::VariablesContainer& variablesContainer) const;
+
+  /**
+   * \brief Return the container of the variables for the specified object or
+   * group of objects.
+   */
+  const gd::VariablesContainer* GetObjectOrGroupVariablesContainer(
+      const gd::String& objectOrGroupName) const;
+
+  /**
+   * \brief Get a type from an object/group variable.
+   */
+  gd::Variable::Type GetTypeOfObjectOrGroupVariable(const gd::String& objectOrGroupName, const gd::String& variableName) const;
+
+  /**
+   * \brief Get a type from an object/group name.
+   * \note If a group contains only objects of a same type, then the group has
+   * this type. Otherwise, it is considered as an object without any specific
+   * type.
+   *
+   * @return Type of the object/group.
+   */
+  gd::String GetTypeOfObject(const gd::String& objectName) const;
+
+  /**
+   * \brief Check if an object or all object of a group has a behavior.
+   */
+  bool HasBehaviorInObjectOrGroup(const gd::String& objectOrGroupName,
+                                  const gd::String& behaviorName) const;
+
+  /**
+   * \brief Get the type of a behavior if an object or all objects of a group
+   * has it.
+   */
+  gd::String GetTypeOfBehaviorInObjectOrGroup(
+      const gd::String& objectOrGroupName,
+      const gd::String& behaviorName,
+      bool searchInGroups = true) const;
+
+  /**
+   * \brief Get a type from a behavior name
+   * @return Type of the behavior.
+   * @deprecated - Use GetTypeOfBehaviorInObjectOrGroup instead.
+   */
+  gd::String GetTypeOfBehavior(const gd::String& behaviorName,
+                               bool searchInGroups = true) const;
+
+  /**
+   * \brief Get behaviors of an object/group
+   * \note The behaviors of a group are the behaviors which are found in common
+   * when looking all the objects of the group.
+   *
+   * @return Vector containing names of behaviors
+   */
+  std::vector<gd::String> GetBehaviorsOfObject(
+      const gd::String& objectName, bool searchInGroups = true) const;
+
+  /**
+   * \brief Return a list containing all objects refered to by the group.
+   * If an object name is passed, then only this object name is returned.
+   *
+   * If \a onlyObjectToSelectIfPresent is set and present in the group(s),
+   * only this object will be returned. This is useful for considering this
+   * object as the "currently selected" object, when generating a condition or
+   * an action.
+   */
+  std::vector<gd::String> ExpandObjectName(
+      const gd::String& objectOrGroupName,
+      const gd::String& onlyObjectToSelectIfPresent = "") const;
+
+  void ForEachObject(std::function<void(const gd::Object& object)> fn) const;
+
+  /**
+   * \brief Call the callback for each object or group name matching the
+   * search passed in parameter.
+   */
+  void ForEachNameMatchingSearch(
+      const gd::String& search,
+      std::function<void(const gd::String& name,
+                         const gd::ObjectConfiguration* objectConfiguration)>
+          fn) const;
+
+  /**
+   * \brief Call the callback for each variable of the object (or group)
+   * matching the search passed in parameter.
+   */
+  void ForEachObjectOrGroupVariableMatchingSearch(
+      const gd::String& objectOrGroupName,
+      const gd::String& search,
+      std::function<void(const gd::String& variableName,
+                         const gd::Variable& variable)> fn) const;
+
+  /** Do not use - should be private but accessible to let Emscripten create a
+   * temporary. */
+  ObjectsContainersList(){};
+
+ private:
+  bool HasObjectNamed(const gd::String& name) const;
+
+  bool HasObjectWithVariableNamed(const gd::String& objectName,
+                                  const gd::String& variableName) const;
+
+  gd::Variable::Type GetTypeOfObjectVariable(const gd::String& objectName, const gd::String& variableName) const;
+
+  void ForEachObjectVariableMatchingSearch(
+      const gd::String& objectOrGroupName,
+      const gd::String& search,
+      std::function<void(const gd::String& variableName,
+                         const gd::Variable& variable)> fn) const;
+
+  void Add(const gd::ObjectsContainer& objectsContainer) {
+    objectsContainers.push_back(&objectsContainer);
+  };
+
+  std::vector<const gd::ObjectsContainer*> objectsContainers;
+};
+
+}  // namespace gd

Core/GDCore/Project/Project.cpp

@@ -48,11 +48,6 @@ using namespace std;
 
 namespace gd {
 
-// By default, disallow unicode in identifiers, but this can be set to true
-// by the IDE. In the future, this will be set to true by default, keeping backward compatibility.
-// We keep it disabled by default to progressively ask users to test it in real projects.
-bool Project::allowUsageOfUnicodeIdentifierNames = false;
-
 Project::Project()
     : name(_("Project")),
       version("1.0.0"),
@@ -86,26 +81,24 @@ Project::~Project() {}
 
 void Project::ResetProjectUuid() { projectUuid = UUID::MakeUuid4(); }
 
-std::unique_ptr<gd::Object>
-Project::CreateObject(const gd::String &objectType, const gd::String &name) const {
-  std::unique_ptr<gd::Object> object =
-      gd::make_unique<Object>(name, objectType, CreateObjectConfiguration(objectType));
+std::unique_ptr<gd::Object> Project::CreateObject(
+    const gd::String& objectType, const gd::String& name) const {
+  std::unique_ptr<gd::Object> object = gd::make_unique<Object>(
+      name, objectType, CreateObjectConfiguration(objectType));
 
-  auto &platform = GetCurrentPlatform();
-  auto &project = *this;
-  auto addDefaultBehavior =
-      [&platform,
-       &project,
-       &object,
-       &objectType](const gd::String& behaviorType) {
-    auto &behaviorMetadata =
+  auto& platform = GetCurrentPlatform();
+  auto& project = *this;
+  auto addDefaultBehavior = [&platform, &project, &object, &objectType](
+                                const gd::String& behaviorType) {
+    auto& behaviorMetadata =
         gd::MetadataProvider::GetBehaviorMetadata(platform, behaviorType);
     if (MetadataProvider::IsBadBehaviorMetadata(behaviorMetadata)) {
-      gd::LogWarning("Object: " + objectType + " has an unknown default behavior: " + behaviorType);
+      gd::LogWarning("Object: " + objectType +
+                     " has an unknown default behavior: " + behaviorType);
       return;
     }
-    auto* behavior = object->AddNewBehavior(project, behaviorType,
-                          behaviorMetadata.GetDefaultName());
+    auto* behavior = object->AddNewBehavior(
+        project, behaviorType, behaviorMetadata.GetDefaultName());
     behavior->SetDefaultBehavior(true);
   };
 
@@ -114,18 +107,17 @@ Project::CreateObject(const gd::String &objectType, const gd::String &name) cons
     addDefaultBehavior("ResizableCapability::ResizableBehavior");
     addDefaultBehavior("ScalableCapability::ScalableBehavior");
     addDefaultBehavior("FlippableCapability::FlippableBehavior");
-  }
-  else {
-    auto &objectMetadata = gd::MetadataProvider::GetObjectMetadata(platform, objectType);
+  } else {
+    auto& objectMetadata =
+        gd::MetadataProvider::GetObjectMetadata(platform, objectType);
     if (MetadataProvider::IsBadObjectMetadata(objectMetadata)) {
       gd::LogWarning("Object: " + name + " has an unknown type: " + objectType);
     }
-    for (auto &behaviorType : objectMetadata.GetDefaultBehaviors()) {
+    for (auto& behaviorType : objectMetadata.GetDefaultBehaviors()) {
       addDefaultBehavior(behaviorType);
     }
   }
 
-  
   return std::move(object);
 }
 
@@ -849,6 +841,11 @@ void Project::UnserializeFrom(const SerializerElement& element) {
   resourcesManager.UnserializeFrom(
       element.GetChild("resources", 0, "Resources"));
   UnserializeObjectsFrom(*this, element.GetChild("objects", 0, "Objects"));
+  if (element.HasChild("objectsFolderStructure")) {
+    UnserializeFoldersFrom(*this, element.GetChild("objectsFolderStructure", 0));
+  }
+  AddMissingObjectsInRootFolder();
+
   GetVariables().UnserializeFrom(element.GetChild("variables", 0, "Variables"));
 
   scenes.clear();
@@ -1000,6 +997,7 @@ void Project::SerializeTo(SerializerElement& element) const {
 
   resourcesManager.SerializeTo(element.AddChild("resources"));
   SerializeObjectsTo(element.AddChild("objects"));
+  SerializeFoldersTo(element.AddChild("objectsFolderStructure"));
   GetObjectGroups().SerializeTo(element.AddChild("objectsGroups"));
   GetVariables().SerializeTo(element.AddChild("variables"));
 
@@ -1038,28 +1036,18 @@ void Project::SerializeTo(SerializerElement& element) const {
         externalSourceFilesElement.AddChild("sourceFile"));
 }
 
-void Project::AllowUsageOfUnicodeIdentifierNames(bool enable) {
-  allowUsageOfUnicodeIdentifierNames = enable;
-}
-
 bool Project::IsNameSafe(const gd::String& name) {
   if (name.empty()) return false;
 
   if (isdigit(name[0])) return false;
 
-  if (!allowUsageOfUnicodeIdentifierNames) {
-    gd::String legacyAllowedCharacters =
-        "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_";
-    return !(name.find_first_not_of(legacyAllowedCharacters) != gd::String::npos);
-  } else {
-    for (auto character : name) {
-      if (!GrammarTerminals::IsAllowedInIdentifier(character)) {
-        return false;
-      }
+  for (auto character : name) {
+    if (!GrammarTerminals::IsAllowedInIdentifier(character)) {
+      return false;
     }
-
-    return true;
   }
+
+  return true;
 }
 
 gd::String Project::GetSafeName(const gd::String& name) {
@@ -1069,18 +1057,13 @@ gd::String Project::GetSafeName(const gd::String& name) {
 
   if (isdigit(name[0])) newName = "_" + newName;
 
-  gd::String legacyAllowedCharacters =
-      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_";
-
-  for (size_t i = 0;i < newName.size();++i) {
-    // Note that iterating on the characters is not super efficient (O(n^2), which
-    // could be avoided with an iterator), but this function is not critical for performance
-    // (only used to generate a name when a user creates a new entity or rename one).
+  for (size_t i = 0; i < newName.size(); ++i) {
+    // Note that iterating on the characters is not super efficient (O(n^2),
+    // which could be avoided with an iterator), but this function is not
+    // critical for performance (only used to generate a name when a user
+    // creates a new entity or rename one).
     auto character = newName[i];
-    bool isAllowed =
-        allowUsageOfUnicodeIdentifierNames
-            ? GrammarTerminals::IsAllowedInIdentifier(character)
-            : legacyAllowedCharacters.find(character) != gd::String::npos;
+    bool isAllowed = GrammarTerminals::IsAllowedInIdentifier(character);
 
     // Replace all unallowed letters by an underscore.
     if (!isAllowed) {

Core/GDCore/Project/Project.h

@@ -11,12 +11,12 @@
 
 #include "GDCore/Project/ExtensionProperties.h"
 #include "GDCore/Project/LoadingScreen.h"
-#include "GDCore/Project/Watermark.h"
 #include "GDCore/Project/ObjectGroupsContainer.h"
 #include "GDCore/Project/ObjectsContainer.h"
 #include "GDCore/Project/PlatformSpecificAssets.h"
 #include "GDCore/Project/ResourcesManager.h"
 #include "GDCore/Project/VariablesContainer.h"
+#include "GDCore/Project/Watermark.h"
 #include "GDCore/String.h"
 namespace gd {
 class Platform;
@@ -82,7 +82,9 @@ class GD_CORE_API Project : public ObjectsContainer {
   /**
    * \brief Change the project description
    */
-  void SetDescription(const gd::String& description_) { description = description_; };
+  void SetDescription(const gd::String& description_) {
+    description = description_;
+  };
 
   /**
    * \brief Get the project description
@@ -124,7 +126,9 @@ class GD_CORE_API Project : public ObjectsContainer {
   /**
    * \brief Get the author usernames of the project.
    */
-  const std::vector<gd::String>& GetAuthorUsernames() const { return authorUsernames; };
+  const std::vector<gd::String>& GetAuthorUsernames() const {
+    return authorUsernames;
+  };
 
   /**
    * \brief Get the author usernames of the project, to modify them (non-const).
@@ -135,7 +139,9 @@ class GD_CORE_API Project : public ObjectsContainer {
    * Define the project as playable with a keyboard.
    * \param enable True to define the project as playable with a keyboard.
    */
-  void SetPlayableWithKeyboard(bool playable = true) { isPlayableWithKeyboard = playable; }
+  void SetPlayableWithKeyboard(bool playable = true) {
+    isPlayableWithKeyboard = playable;
+  }
 
   /**
    * Check if the project is defined as playable with a keyboard.
@@ -146,7 +152,9 @@ class GD_CORE_API Project : public ObjectsContainer {
    * Define the project as playable with a gamepad.
    * \param enable True to define the project as playable with a gamepad.
    */
-  void SetPlayableWithGamepad(bool playable = true) { isPlayableWithGamepad = playable; }
+  void SetPlayableWithGamepad(bool playable = true) {
+    isPlayableWithGamepad = playable;
+  }
 
   /**
    * Check if the project is defined as playable with a gamepad.
@@ -157,7 +165,9 @@ class GD_CORE_API Project : public ObjectsContainer {
    * Define the project as playable on a mobile.
    * \param enable True to define the project as playable on a mobile.
    */
-  void SetPlayableWithMobile(bool playable = true) { isPlayableWithMobile = playable; }
+  void SetPlayableWithMobile(bool playable = true) {
+    isPlayableWithMobile = playable;
+  }
 
   /**
    * Check if the project is defined as playable on a mobile.
@@ -391,17 +401,23 @@ class GD_CORE_API Project : public ObjectsContainer {
   /**
    * Set the antialiasing mode used by the game ("none" or "MSAA").
    */
-  void SetAntialiasingMode(const gd::String& antialiasingMode_) { antialiasingMode = antialiasingMode_; }
+  void SetAntialiasingMode(const gd::String& antialiasingMode_) {
+    antialiasingMode = antialiasingMode_;
+  }
 
   /**
    * Return true if antialising is enabled on mobiles.
    */
-  bool IsAntialisingEnabledOnMobile() const { return isAntialisingEnabledOnMobile; }
+  bool IsAntialisingEnabledOnMobile() const {
+    return isAntialisingEnabledOnMobile;
+  }
 
   /**
    * Set whether antialising is enabled on mobiles or not.
    */
-  void SetAntialisingEnabledOnMobile(bool enable) { isAntialisingEnabledOnMobile = enable; }
+  void SetAntialisingEnabledOnMobile(bool enable) {
+    isAntialisingEnabledOnMobile = enable;
+  }
 
   /**
    * \brief Return if the project should set 0 as Z-order for objects created
@@ -905,7 +921,8 @@ class GD_CORE_API Project : public ObjectsContainer {
   /**
    * \brief Return the events based object with a given type.
    */
-  const gd::EventsBasedObject& GetEventsBasedObject(const gd::String& type) const;
+  const gd::EventsBasedObject& GetEventsBasedObject(
+      const gd::String& type) const;
 
   /**
    * \brief  Check if events based behavior with a given type exists.
@@ -920,7 +937,8 @@ class GD_CORE_API Project : public ObjectsContainer {
   /**
    * \brief Return the events based behavior with a given type.
    */
-  const gd::EventsBasedBehavior& GetEventsBasedBehavior(const gd::String& type) const;
+  const gd::EventsBasedBehavior& GetEventsBasedBehavior(
+      const gd::String& type) const;
 
   ///@}
 
@@ -969,20 +987,6 @@ class GD_CORE_API Project : public ObjectsContainer {
    */
   ///@{
 
-  /**
-   * Check if unicode names are allowed in identifier names.
-   * \see IsNameSafe
-   * \see GetSafeName
-   */
-  static bool IsUsageOfUnicodeIdentifierNamesAllowed() { return allowUsageOfUnicodeIdentifierNames; };
-
-  /**
-   * Set if unicode names are allowed in identifier names.
-   * \see IsNameSafe
-   * \see GetSafeName
-   */
-  static void AllowUsageOfUnicodeIdentifierNames(bool enable);
-
   /**
    * Return true if \a name is valid (can be used safely for an object,
    * behavior, events function name, etc...).
@@ -990,8 +994,8 @@ class GD_CORE_API Project : public ObjectsContainer {
   static bool IsNameSafe(const gd::String& name);
 
   /**
-   * Return a name, based on the one passed in parameter, that can be safely used
-   * for an object, behavior, events function name, etc...
+   * Return a name, based on the one passed in parameter, that can be safely
+   * used for an object, behavior, events function name, etc...
    */
   static gd::String GetSafeName(const gd::String& name);
   ///@}
@@ -1068,8 +1072,8 @@ class GD_CORE_API Project : public ObjectsContainer {
   bool adaptGameResolutionAtRuntime;  ///< Should the game resolution be adapted
                                       ///< to the window size at runtime
   gd::String
-      sizeOnStartupMode;   ///< How to adapt the game size to the screen. Can be
-                           ///< "adaptWidth", "adaptHeight" or empty
+      sizeOnStartupMode;  ///< How to adapt the game size to the screen. Can be
+                          ///< "adaptWidth", "adaptHeight" or empty
   gd::String antialiasingMode;
   bool isAntialisingEnabledOnMobile;
   gd::String projectUuid;  ///< UUID useful to identify the game in online
@@ -1095,19 +1099,18 @@ class GD_CORE_API Project : public ObjectsContainer {
       externalSourceFiles;  ///< List of external source files used.
   gd::String author;        ///< Game author name, for publishing purpose.
   std::vector<gd::String>
-      authorIds;           ///< Game author ids, from GDevelop users DB.
+      authorIds;  ///< Game author ids, from GDevelop users DB.
   std::vector<gd::String>
-      authorUsernames;     ///< Game author usernames, from GDevelop users DB.
-  std::vector<gd::String>
-      categories;           ///< Game categories
-  bool isPlayableWithKeyboard; ///< The project is playable with a keyboard.
-  bool isPlayableWithGamepad;  ///< The project is playable with a gamepad.
-  bool isPlayableWithMobile;   ///< The project is playable on a mobile.
-  gd::String packageName;  ///< Game package name
-  gd::String templateSlug; ///< The slug of the template from which the game is
-                           ///< created.
-  gd::String orientation;  ///< Lock game orientation (on mobile devices).
-                           ///< "default", "landscape" or "portrait".
+      authorUsernames;  ///< Game author usernames, from GDevelop users DB.
+  std::vector<gd::String> categories;  ///< Game categories
+  bool isPlayableWithKeyboard;  ///< The project is playable with a keyboard.
+  bool isPlayableWithGamepad;   ///< The project is playable with a gamepad.
+  bool isPlayableWithMobile;    ///< The project is playable on a mobile.
+  gd::String packageName;       ///< Game package name
+  gd::String templateSlug;  ///< The slug of the template from which the game is
+                            ///< created.
+  gd::String orientation;   ///< Lock game orientation (on mobile devices).
+                            ///< "default", "landscape" or "portrait".
   bool
       folderProject;  ///< True if folder project, false if single file project.
   gd::String
@@ -1128,8 +1131,6 @@ class GD_CORE_API Project : public ObjectsContainer {
                                         ///< time the project was saved.
   mutable unsigned int gdBuildVersion;  ///< The GD build version used the last
                                         ///< time the project was saved.
-
-  static bool allowUsageOfUnicodeIdentifierNames;
 };
 
 }  // namespace gd

Core/GDCore/Project/ProjectScopedContainers.h

@@ -0,0 +1,174 @@
+#pragma once
+#include <set>
+
+#include "GDCore/Extensions/Metadata/ParameterMetadataTools.h"
+#include "ObjectsContainersList.h"
+#include "PropertiesContainersList.h"
+#include "VariablesContainersList.h"
+
+namespace gd {
+class Project;
+class ObjectsContainer;
+class ObjectsContainersList;
+class VariablesContainersList;
+class PropertiesContainersList;
+class NamedPropertyDescriptor;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief Holds references to variables, objects, properties and other
+ * containers.
+ *
+ * This is useful to access elements of a project from a specific location,
+ * honoring the scope of each element.
+ *
+ * For example, in an expression, when an identifier is written, this class is
+ * used to know what this identifier refers too.
+ */
+class ProjectScopedContainers {
+ public:
+  ProjectScopedContainers(
+      const gd::ObjectsContainersList &objectsContainersList_,
+      const gd::VariablesContainersList &variablesContainersList_,
+      const gd::PropertiesContainersList &propertiesContainersList_)
+      : objectsContainersList(objectsContainersList_),
+        variablesContainersList(variablesContainersList_),
+        propertiesContainersList(propertiesContainersList_){};
+  virtual ~ProjectScopedContainers(){};
+
+  static ProjectScopedContainers
+  MakeNewProjectScopedContainersForProjectAndLayout(const gd::Project &project,
+                                                    const gd::Layout &layout) {
+    ProjectScopedContainers projectScopedContainers(
+        ObjectsContainersList::MakeNewObjectsContainersListForProjectAndLayout(
+            project, layout),
+        VariablesContainersList::
+            MakeNewVariablesContainersListForProjectAndLayout(project, layout),
+        PropertiesContainersList::MakeNewEmptyPropertiesContainersList());
+
+    return projectScopedContainers;
+  }
+
+  static ProjectScopedContainers MakeNewProjectScopedContainersFor(
+      const gd::ObjectsContainer &globalObjectsContainers,
+      const gd::ObjectsContainer &objectsContainers) {
+    ProjectScopedContainers projectScopedContainers(
+        ObjectsContainersList::MakeNewObjectsContainersListForContainers(
+            globalObjectsContainers, objectsContainers),
+        VariablesContainersList::MakeNewEmptyVariablesContainersList(),
+        PropertiesContainersList::MakeNewEmptyPropertiesContainersList());
+
+    return projectScopedContainers;
+  }
+
+  ProjectScopedContainers &AddPropertiesContainer(
+      const gd::PropertiesContainer &container) {
+    propertiesContainersList.Add(container);
+
+    return *this;
+  }
+
+  ProjectScopedContainers &AddParameters(
+      const std::vector<gd::ParameterMetadata> &parameters) {
+    parametersVectorsList.push_back(&parameters);
+
+    return *this;
+  }
+
+  template <class ReturnType>
+  ReturnType MatchIdentifierWithName(
+      const gd::String &name,
+      std::function<ReturnType()> objectCallback,
+      std::function<ReturnType()> variableCallback,
+      std::function<ReturnType()> propertyCallback,
+      std::function<ReturnType()> parameterCallback,
+      std::function<ReturnType()> notFoundCallback) const {
+    if (objectsContainersList.HasObjectOrGroupNamed(name))
+      return objectCallback();
+    else if (variablesContainersList.Has(name))
+      return variableCallback();
+    else if (ParameterMetadataTools::Has(parametersVectorsList, name))
+      return parameterCallback();
+    else if (propertiesContainersList.Has(name))
+      return propertyCallback();
+
+    return notFoundCallback();
+  };
+
+  void ForEachIdentifierMatchingSearch(
+      const gd::String &search,
+      std::function<void(const gd::String &name,
+                         const ObjectConfiguration *objectConfiguration)>
+          objectCallback,
+      std::function<void(const gd::String &name, const gd::Variable &variable)>
+          variableCallback,
+      std::function<void(const gd::NamedPropertyDescriptor &property)>
+          propertyCallback,
+      std::function<void(const gd::ParameterMetadata &parameter)>
+          parameterCallback) const {
+    std::set<gd::String> namesAlreadySeen;
+
+    objectsContainersList.ForEachNameMatchingSearch(
+        search,
+        [&](const gd::String &name,
+            const ObjectConfiguration *objectConfiguration) {
+          if (namesAlreadySeen.count(name) == 0) {
+            namesAlreadySeen.insert(name);
+            objectCallback(name, objectConfiguration);
+          }
+        });
+    variablesContainersList.ForEachVariableMatchingSearch(
+        search, [&](const gd::String &name, const gd::Variable &variable) {
+          if (namesAlreadySeen.count(name) == 0) {
+            namesAlreadySeen.insert(name);
+            variableCallback(name, variable);
+          }
+        });
+    gd::ParameterMetadataTools::ForEachParameterMatchingSearch(
+        parametersVectorsList,
+        search,
+        [&](const gd::ParameterMetadata &parameter) {
+          if (namesAlreadySeen.count(parameter.GetName()) == 0) {
+            namesAlreadySeen.insert(parameter.GetName());
+            parameterCallback(parameter);
+          }
+        });
+    propertiesContainersList.ForEachPropertyMatchingSearch(
+        search, [&](const gd::NamedPropertyDescriptor &property) {
+          if (namesAlreadySeen.count(property.GetName()) == 0) {
+            namesAlreadySeen.insert(property.GetName());
+            propertyCallback(property);
+          }
+        });
+  };
+
+  const gd::ObjectsContainersList &GetObjectsContainersList() const {
+    return objectsContainersList;
+  };
+
+  const gd::VariablesContainersList &GetVariablesContainersList() const {
+    return variablesContainersList;
+  };
+
+  const gd::PropertiesContainersList &GetPropertiesContainersList() const {
+    return propertiesContainersList;
+  };
+
+  const std::vector<const std::vector<gd::ParameterMetadata> *> &GetParametersVectorsList() const {
+    return parametersVectorsList;
+  };
+
+  /** Do not use - should be private but accessible to let Emscripten create a
+   * temporary. */
+  ProjectScopedContainers(){};
+
+ private:
+  gd::ObjectsContainersList objectsContainersList;
+  gd::VariablesContainersList variablesContainersList;
+  gd::PropertiesContainersList propertiesContainersList;
+  std::vector<const std::vector<gd::ParameterMetadata> *> parametersVectorsList;
+};
+
+}  // namespace gd

Core/GDCore/Project/PropertiesContainer.h

@@ -0,0 +1,50 @@
+#pragma once
+#include "EventsFunctionsContainer.h"
+#include "GDCore/Tools/SerializableWithNameList.h"
+#include "NamedPropertyDescriptor.h"
+
+namespace gd {
+
+/**
+ * \brief A container of properties, used for custom behaviors, custom objects,
+ * extensions...
+ *
+ * \see gd::NamedPropertyDescriptor
+ *
+ * \ingroup PlatformDefinition
+ */
+class PropertiesContainer
+    : public SerializableWithNameList<NamedPropertyDescriptor> {
+ public:
+  PropertiesContainer(EventsFunctionsContainer::FunctionOwner owner)
+      : SerializableWithNameList<NamedPropertyDescriptor>(), owner(owner) {}
+
+  PropertiesContainer(const PropertiesContainer& other)
+      : SerializableWithNameList<NamedPropertyDescriptor>(other),
+        owner(other.owner) {}
+
+  PropertiesContainer& operator=(const PropertiesContainer& other) {
+    if (this != &other) {
+      SerializableWithNameList<NamedPropertyDescriptor>::operator=(other);
+      owner = other.owner;
+    }
+    return *this;
+  }
+
+  void ForEachPropertyMatchingSearch(
+      const gd::String& search,
+      std::function<void(const gd::NamedPropertyDescriptor& property)> fn)
+      const {
+    for (const auto& property : elements) {
+      if (property->GetName().FindCaseInsensitive(search) != gd::String::npos)
+        fn(*property);
+    }
+  }
+
+  EventsFunctionsContainer::FunctionOwner GetOwner() const { return owner; }
+
+ private:
+  EventsFunctionsContainer::FunctionOwner owner;
+};
+
+}  // namespace gd

Core/GDCore/Project/PropertiesContainersList.cpp

@@ -0,0 +1,67 @@
+#include "PropertiesContainersList.h"
+
+#include <functional>
+#include <vector>
+
+#include "PropertiesContainer.h"
+
+namespace gd {
+
+NamedPropertyDescriptor PropertiesContainersList::badNamedPropertyDescriptor;
+PropertiesContainer PropertiesContainersList::badPropertiesContainer(gd::EventsFunctionsContainer::FunctionOwner::Extension);
+
+PropertiesContainersList
+PropertiesContainersList::MakeNewPropertiesContainersListFor(
+    const gd::PropertiesContainer& propertiesContainer) {
+  PropertiesContainersList propertiesContainersList;
+  propertiesContainersList.Add(propertiesContainer);
+  return propertiesContainersList;
+}
+
+PropertiesContainersList
+PropertiesContainersList::MakeNewEmptyPropertiesContainersList() {
+  PropertiesContainersList propertiesContainersList;
+  return propertiesContainersList;
+}
+
+bool PropertiesContainersList::Has(const gd::String& name) const {
+  for (auto it = propertiesContainers.rbegin();
+       it != propertiesContainers.rend();
+       ++it) {
+    if ((*it)->Has(name)) return true;
+  }
+
+  return false;
+}
+
+std::pair<std::reference_wrapper<const gd::PropertiesContainer>,
+          std::reference_wrapper<const NamedPropertyDescriptor>>
+PropertiesContainersList::Get(const gd::String& name) const {
+  for (auto it = propertiesContainers.rbegin();
+       it != propertiesContainers.rend();
+       ++it) {
+    if ((*it)->Has(name)) return {**it, (*it)->Get(name)};
+  }
+
+  return {badPropertiesContainer, badNamedPropertyDescriptor};
+}
+
+bool PropertiesContainersList::HasPropertiesContainer(const gd::PropertiesContainer& propertiesContainer) const {
+  for (auto it = propertiesContainers.rbegin(); it != propertiesContainers.rend();
+       ++it) {
+    if (*it == &propertiesContainer) return true;
+  }
+
+  return false;
+}
+
+void PropertiesContainersList::ForEachPropertyMatchingSearch(
+    const gd::String& search,
+    std::function<void(const gd::NamedPropertyDescriptor& property)> fn) const {
+  for (auto it = propertiesContainers.rbegin(); it != propertiesContainers.rend();
+       ++it) {
+    (*it)->ForEachPropertyMatchingSearch(search, fn);
+  }
+}
+
+}  // namespace gd

Core/GDCore/Project/PropertiesContainersList.h

@@ -0,0 +1,84 @@
+#pragma once
+#include <functional>
+#include <vector>
+
+#include "PropertiesContainer.h"
+
+namespace gd {
+class String;
+class Project;
+class Layout;
+class NamedPropertyDescriptor;
+}  // namespace gd
+
+namespace gd {
+
+/**
+ * \brief A list of property containers, useful for accessing properties in a
+ * scoped way.
+ *
+ * \see gd::NamedPropertyDescriptor
+ * \see gd::Project
+ * \see gd::Layout
+ *
+ * \ingroup PlatformDefinition
+ */
+class GD_CORE_API PropertiesContainersList {
+ public:
+  virtual ~PropertiesContainersList(){};
+
+  static PropertiesContainersList MakeNewPropertiesContainersListFor(
+      const gd::PropertiesContainer& propertiesContainer);
+  static PropertiesContainersList MakeNewEmptyPropertiesContainersList();
+
+  /**
+   * \brief Add a new container of properties in the list.
+   * Add containers in order from the most global one to the most local one.
+   */
+  void Add(const gd::PropertiesContainer& propertiesContainer) {
+    propertiesContainers.push_back(&propertiesContainer);
+  };
+
+  /**
+   * \brief Return true if the specified property is in one of the containers.
+   */
+  bool Has(const gd::String& name) const;
+
+  /**
+   * \brief Return a reference to the property called \a name, and the
+   * properties container holding it.
+   */
+  std::pair<std::reference_wrapper<const gd::PropertiesContainer>,
+            std::reference_wrapper<const NamedPropertyDescriptor>>
+  Get(const gd::String& name) const;
+
+  /**
+   * \brief Return true if the specified properties container is present.
+   */
+  bool HasPropertiesContainer(const gd::PropertiesContainer& propertiesContainer) const;
+
+  /**
+   * Get the properties container at the bottom of the scope (so the most
+   * "local" one).
+   */
+  const PropertiesContainer* GetBottomMostPropertiesContainer() const {
+    if (propertiesContainers.empty()) return nullptr;
+    return propertiesContainers.back();
+  }
+
+  /**
+   * \brief Call the callback for each property having a name matching the specified search.
+   */
+  void ForEachPropertyMatchingSearch(const gd::String& search, std::function<void(const gd::NamedPropertyDescriptor& property)> fn) const;
+
+  /** Do not use - should be private but accessible to let Emscripten create a
+   * temporary. */
+  PropertiesContainersList(){};
+
+ private:
+  std::vector<const gd::PropertiesContainer*> propertiesContainers;
+  static NamedPropertyDescriptor badNamedPropertyDescriptor;
+  static PropertiesContainer badPropertiesContainer;
+};
+
+}  // namespace gd

Core/GDCore/Project/Variable.cpp

@@ -10,6 +10,7 @@
 
 #include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/String.h"
+#include "GDCore/Tools/UUID/UUID.h"
 
 using namespace std;
 
@@ -228,6 +229,9 @@ void Variable::SerializeTo(SerializerElement& element) const {
   element.SetStringAttribute("type", TypeAsString(GetType()));
   if (IsFolded()) element.SetBoolAttribute("folded", true);
 
+  if (!persistentUuid.empty())
+    element.SetStringAttribute("persistentUuid", persistentUuid);
+
   if (type == Type::String) {
     element.SetStringAttribute("value", GetString());
   } else if (type == Type::Number) {
@@ -254,6 +258,8 @@ void Variable::SerializeTo(SerializerElement& element) const {
 void Variable::UnserializeFrom(const SerializerElement& element) {
   type = StringAsType(element.GetStringAttribute("type", "string"));
 
+  persistentUuid = element.GetStringAttribute("persistentUuid");
+
   // Compatibility with GD <= 5.0.0-beta102
   // Before, everything was stored as strings.
   // We can unserialize primitives as string as they can be converted from/to
@@ -290,7 +296,12 @@ void Variable::UnserializeFrom(const SerializerElement& element) {
         PushNew().UnserializeFrom(childElement);
     }
   }
-}  // namespace gd
+}
+
+Variable& Variable::ResetPersistentUuid() {
+  persistentUuid = UUID::MakeUuid4();
+  return *this;
+}
 
 std::vector<gd::String> Variable::GetAllChildrenNames() const {
   std::vector<gd::String> names;
@@ -338,7 +349,8 @@ Variable::Variable(const Variable& other)
       str(other.str),
       folded(other.folded),
       boolVal(other.boolVal),
-      type(other.type) {
+      type(other.type),
+      persistentUuid(other.persistentUuid) {
   CopyChildren(other);
 }
 
@@ -349,6 +361,7 @@ Variable& Variable::operator=(const Variable& other) {
     folded = other.folded;
     boolVal = other.boolVal;
     type = other.type;
+    persistentUuid = other.persistentUuid;
     CopyChildren(other);
   }
 

Core/GDCore/Project/Variable.h

@@ -338,6 +338,24 @@ class GD_CORE_API Variable {
    * \brief Unserialize the variable.
    */
   void UnserializeFrom(const SerializerElement& element);
+
+  /**
+   * \brief Reset the persistent UUID used to recognize
+   * the same variable between serialization.
+   */
+  Variable& ResetPersistentUuid();
+
+  /**
+   * \brief Remove the persistent UUID - when the variable no
+   * longer needs to be recognized between serializations.
+   */
+  Variable& ClearPersistentUuid() { persistentUuid = ""; return *this; };
+
+  /**
+   * \brief Get the persistent UUID used to recognize
+   * the same variable between serialization.
+   */
+  const gd::String& GetPersistentUuid() const { return persistentUuid; };
   ///@}
 
  private:
@@ -361,6 +379,8 @@ class GD_CORE_API Variable {
   mutable std::vector<std::shared_ptr<Variable>>
       childrenArray;  ///< Children, when the variable is considered as an
                       ///< array.
+  mutable gd::String persistentUuid;  ///< A persistent random version 4 UUID,
+                                      ///< useful for computing changesets.
 
   /**
    * Initialize children by copying them from another variable.  Used by

Core/GDCore/Project/VariablesContainer.cpp

@@ -12,6 +12,7 @@
 #include "GDCore/Serialization/SerializerElement.h"
 #include "GDCore/String.h"
 #include "GDCore/TinyXml/tinyxml.h"
+#include "GDCore/Tools/UUID/UUID.h"
 
 namespace gd {
 
@@ -161,7 +162,20 @@ void VariablesContainer::Move(std::size_t oldIndex, std::size_t newIndex) {
   variables.insert(variables.begin() + newIndex, nameAndVariable);
 }
 
+void VariablesContainer::ForEachVariableMatchingSearch(
+    const gd::String& search,
+    std::function<void(const gd::String& name, const gd::Variable& variable)>
+        fn) const {
+  for (const auto& nameAndVariable : variables) {
+    if (nameAndVariable.first.FindCaseInsensitive(search) != gd::String::npos)
+      fn(nameAndVariable.first, *nameAndVariable.second);
+  }
+}
+
 void VariablesContainer::SerializeTo(SerializerElement& element) const {
+  if (!persistentUuid.empty())
+    element.SetStringAttribute("persistentUuid", persistentUuid);
+
   element.ConsiderAsArrayOf("variable");
   for (std::size_t j = 0; j < variables.size(); j++) {
     SerializerElement& variableElement = element.AddChild("variable");
@@ -171,6 +185,8 @@ void VariablesContainer::SerializeTo(SerializerElement& element) const {
 }
 
 void VariablesContainer::UnserializeFrom(const SerializerElement& element) {
+  persistentUuid = element.GetStringAttribute("persistentUuid");
+
   Clear();
   element.ConsiderAsArrayOf("variable", "Variable");
   for (std::size_t j = 0; j < element.GetChildrenCount(); j++) {
@@ -183,6 +199,24 @@ void VariablesContainer::UnserializeFrom(const SerializerElement& element) {
   }
 }
 
+VariablesContainer& VariablesContainer::ResetPersistentUuid() {
+  persistentUuid = UUID::MakeUuid4();
+  for (auto& variable : variables) {
+    variable.second->ResetPersistentUuid();
+  }
+
+  return *this;
+}
+
+VariablesContainer& VariablesContainer::ClearPersistentUuid() {
+  persistentUuid = "";
+  for (auto& variable : variables) {
+    variable.second->ClearPersistentUuid();
+  }
+
+  return *this;
+}
+
 VariablesContainer::VariablesContainer(const VariablesContainer& other) {
   Init(other);
 }
@@ -195,6 +229,7 @@ VariablesContainer& VariablesContainer::operator=(
 }
 
 void VariablesContainer::Init(const gd::VariablesContainer& other) {
+  persistentUuid = other.persistentUuid;
   variables.clear();
   for (auto& it : other.variables) {
     variables.push_back(

Core/GDCore/Project/VariablesContainer.h

@@ -137,6 +137,11 @@ class GD_CORE_API VariablesContainer {
    * \brief Clear all variables of the container.
    */
   inline void Clear() { variables.clear(); }
+
+  /**
+   * \brief Call the callback for each variable with a name matching the specified search.
+   */
+  void ForEachVariableMatchingSearch(const gd::String& search, std::function<void(const gd::String& name, const gd::Variable& variable)> fn) const;
   ///@}
 
   /** \name Saving and loading
@@ -152,10 +157,30 @@ class GD_CORE_API VariablesContainer {
    * \brief Unserialize the variable container.
    */
   void UnserializeFrom(const SerializerElement& element);
+
+  /**
+   * \brief Reset the persistent UUID, used to recognize
+   * the same variables between serialization.
+   */
+  VariablesContainer& ResetPersistentUuid();
+
+  /**
+   * \brief Remove the persistent UUID - when the variables no
+   * longer need to be recognized between serializations.
+   */
+  VariablesContainer& ClearPersistentUuid();
+
+  /**
+   * \brief Get the persistent UUID used to recognize
+   * the same variables between serialization.
+   */
+  const gd::String& GetPersistentUuid() const { return persistentUuid; };
   ///@}
 
  private:
   std::vector<std::pair<gd::String, std::shared_ptr<gd::Variable>>> variables;
+  mutable gd::String persistentUuid;  ///< A persistent random version 4 UUID,
+                                      ///< useful for computing changesets.
   static gd::Variable badVariable;
   static gd::String badName;
 

Core/GDCore/Project/VariablesContainersList.cpp

@@ -0,0 +1,64 @@
+#include "VariablesContainersList.h"
+
+#include <vector>
+
+#include "GDCore/Project/Layout.h"
+#include "GDCore/Project/Project.h"
+#include "GDCore/Project/Variable.h"
+
+namespace gd {
+
+Variable VariablesContainersList::badVariable;
+
+VariablesContainersList
+VariablesContainersList::MakeNewVariablesContainersListForProjectAndLayout(
+    const gd::Project& project, const gd::Layout& layout) {
+  VariablesContainersList variablesContainersList;
+  variablesContainersList.Add(project.GetVariables());
+  variablesContainersList.Add(layout.GetVariables());
+  return variablesContainersList;
+}
+
+VariablesContainersList
+VariablesContainersList::MakeNewEmptyVariablesContainersList() {
+  VariablesContainersList variablesContainersList;
+  return variablesContainersList;
+}
+
+bool VariablesContainersList::Has(const gd::String& name) const {
+  for (auto it = variablesContainers.rbegin(); it != variablesContainers.rend();
+       ++it) {
+    if ((*it)->Has(name)) return true;
+  }
+
+  return false;
+}
+
+const Variable& VariablesContainersList::Get(const gd::String& name) const {
+  for (auto it = variablesContainers.rbegin(); it != variablesContainers.rend();
+       ++it) {
+    if ((*it)->Has(name)) return (*it)->Get(name);
+  }
+
+  return badVariable;
+}
+
+bool VariablesContainersList::HasVariablesContainer(const gd::VariablesContainer& variablesContainer) const {
+  for (auto it = variablesContainers.rbegin(); it != variablesContainers.rend();
+       ++it) {
+    if (*it == &variablesContainer) return true;
+  }
+
+  return false;
+}
+
+void VariablesContainersList::ForEachVariableMatchingSearch(
+    const gd::String& search,
+    std::function<void(const gd::String& name, const gd::Variable& variable)> fn) const {
+  for (auto it = variablesContainers.rbegin(); it != variablesContainers.rend();
+       ++it) {
+    (*it)->ForEachVariableMatchingSearch(search, fn);
+  }
+}
+
+}  // namespace gd