feat: Remove need for .cast

By adding the script instance check to `gd_object_to_dart_object`, that method can do all casting for us properly.

Minor: fix generator to not have RPC method class be private (preventing a warning from the analyzer).

Author: fuzzybinary

README.md

@@ -100,7 +100,7 @@ class SimpleScript extends Sprite2D  {
   // Any method that needs to be seen by a signal needs to be exported
   @GodotExport()
   void onSignal() {
-    // To call and RPC as an RPC you use the $rpc variable
+    // To call an RPC as an RPC you use the $rpc variable
     $rpc.rpcMessage('message');
   }
 }
@@ -133,8 +133,7 @@ class Simple extends Sprite2D {
     StringName.fromString('Simple'),
     parentClass: StringName.fromString('Sprite2D'),
     // a vTable getter is required for classes that will be used from extensions.
-    // If you are not adding any virtual functions, just return the base class's vTable.
-    // If the class is only used from scripts, this is likely not necessary.
+    // If you are not adding any virtual functions, just return the base class's vTable.    
     vTable: Sprite2D.sTypeInfo.vTable;
   );
   // An override of [typeInfo] is required. This is how
@@ -184,9 +183,9 @@ void main() {
 
 ### Casting
 
-When you are working with a Godot object, do not use `is` or `as` to perform downcasting. This will
-always fail because of how Godot extension works. Instead, use `.cast<T>`, which will return `null`
-if the cast fails.
+Early versions of Godot Dart required using `.cast<T>` to perform downcasting. This is no longer
+necessary. Dart's built in `is` and `as` operators should now work to perform downcasting. `cast<T>` 
+has also been removed and replaced with `.as<T>`, which is an implementation of `as?` or `dynamic_cast`.
 
 ### Virtual functions
 

example/2d_tutorial/src/lib/game_logic.dart

@@ -75,7 +75,7 @@ class GameLogic extends Node {
 
   @GodotExport()
   void onMobTimerTimeout() {
-    final mob = mobScene?.instantiate()?.cast<Mob>();
+    final mob = mobScene?.instantiate()?.as<Mob>();
     if (mob != null) {
       var mobSpawnLocation =
           getNodeT<PathFollow2D>('MobPath/MobSpawnLocation')!;

src/cpp/dart_bindings.cpp

@@ -397,18 +397,18 @@ void GodotDartBindings::bind_method(const TypeInfo &bind_type, const char *metho
 Dart_Handle GodotDartBindings::find_dart_type(Dart_Handle type_name) {
   DartBlockScope scope;
 
-  uint8_t* c_type_name = nullptr;
+  uint8_t *c_type_name = nullptr;
   intptr_t length = 0;
   Dart_StringToUTF8(type_name, &c_type_name, &length);
-  if (0 == strncmp(reinterpret_cast<const char*>(c_type_name), "Object", length)) {
+  if (0 == strncmp(reinterpret_cast<const char *>(c_type_name), "Object", length)) {
     type_name = Dart_NewStringFromCString("GodotObject");
   }
 
   DART_CHECK_RET(engine_classes_library, Dart_HandleFromPersistent(_engine_classes_library), Dart_Null(),
-    "Error getting class class library.")
+                 "Error getting class class library.")
 
   DART_CHECK_RET(type, Dart_GetNonNullableType(engine_classes_library, type_name, 0, nullptr), Dart_Null(),
-    "Could not find type in the engine_classes_library.");
+                 "Could not find type in the engine_classes_library.");
 
   return type;
 }
@@ -815,9 +815,17 @@ void gd_object_to_dart_object(Dart_NativeArguments args) {
   }
 
   GDEWrapper *gde = GDEWrapper::instance();
+  GDExtensionScriptInstanceDataPtr script_instance = gde_object_get_script_instance(
+      reinterpret_cast<GDExtensionObjectPtr>(object_ptr), DartScriptLanguage::instance()->_owner);
+  if (script_instance) {
+    Dart_Handle obj = reinterpret_cast<DartScriptInstance *>(script_instance)->get_dart_object();
+    Dart_SetReturnValue(args, obj);
+    return;
+  }
 
   DartGodotInstanceBinding *binding = (DartGodotInstanceBinding *)gde_object_get_instance_binding(
-      reinterpret_cast<GDExtensionObjectPtr>(object_ptr), bindings, &DartGodotInstanceBinding::engine_binding_callbacks);
+      reinterpret_cast<GDExtensionObjectPtr>(object_ptr), bindings,
+      &DartGodotInstanceBinding::engine_binding_callbacks);
   if (binding == nullptr) {
     Dart_SetReturnValue(args, Dart_Null());
   } else {
@@ -905,7 +913,7 @@ void type_info_from_dart(TypeInfo *type_info, Dart_Handle dart_type_info) {
 
   Dart_Handle class_name = Dart_GetField(dart_type_info, Dart_NewStringFromCString("className"));
   Dart_Handle parent_type = Dart_GetField(dart_type_info, Dart_NewStringFromCString("parentType"));
-  Dart_Handle variant_type = Dart_GetField(dart_type_info, Dart_NewStringFromCString("variantType"));  
+  Dart_Handle variant_type = Dart_GetField(dart_type_info, Dart_NewStringFromCString("variantType"));
 
   type_info->type_name = get_object_address(class_name);
   type_info->parent_type = parent_type;
@@ -938,8 +946,8 @@ GDE_EXPORT void tie_dart_to_native(Dart_Handle dart_object, GDExtensionObjectPtr
   type_info_from_dart(&class_type_info, d_class_type_info);
 
   const GDExtensionInstanceBindingCallbacks *callbacks = &DartGodotInstanceBinding::engine_binding_callbacks;
-  DartGodotInstanceBinding *binding = (DartGodotInstanceBinding *)gde_object_get_instance_binding(
-      godot_object, bindings, callbacks);
+  DartGodotInstanceBinding *binding =
+      (DartGodotInstanceBinding *)gde_object_get_instance_binding(godot_object, bindings, callbacks);
   if (!binding->is_initialized()) {
     binding->initialize(dart_object, is_refcounted);
   }

src/dart/godot_dart/lib/src/core/gdextension.dart

@@ -212,37 +212,8 @@ class GodotDart {
 }
 
 extension GodotObjectCast on GodotObject {
-  // TODO: We might not need this if gdObjectToDartObject checks
-  // if something has a script instance, than casts it directly.
-  T? cast<T>() {
-    var typeInfo = gde.dartBindings.getGodotTypeInfo(T);
-    final classTag = gde.getClassTag(typeInfo.className);
-    Pointer<Void> casted;
-    if (classTag != nullptr) {
-      casted = gde.ffiBindings.gde_object_cast_to(nativePtr, classTag);
-      if (casted == nullptr) {
-        return null;
-      }
-
-      final persistent = gde.ffiBindings.gde_object_get_instance_binding(
-        casted,
-        gde.extensionToken,
-        gde.engineBindingCallbacks,
-      );
-      final dartObject = gde.dartBindings.objectFromInstanceBinding(persistent);
-
-      return dartObject as T;
-    } else {
-      // Try getting the script instance, and casting from that
-      final scriptInstance = gde.dartBindings.getScriptInstance(nativePtr);
-      if (scriptInstance != nullptr) {
-        final o = gde.dartBindings.objectFromScriptInstance(scriptInstance);
-        if (o is T) {
-          return o;
-        }
-      }
-    }
-
-    return null;
+  // Implementation of as? or dynamic_cast
+  T? as<T>() {
+    return this is T ? this as T : null;
   }
 }

src/dart/godot_dart/lib/src/core/type_info.dart

@@ -120,7 +120,7 @@ class TypeInfo {
     this.size = 0,
     this.vTable = const {},
     this.scriptInfo,
-  }) {}
+  });
 
   static late Map<Type?, TypeInfo> _typeMapping;
   static void initTypeMappings() {

src/dart/godot_dart/lib/src/extensions/core_extensions.dart

@@ -15,7 +15,7 @@ extension TNode on Node {
       name = GDString.fromStringName(typeInfo.className);
     }
     var node = getNode(NodePath.fromGDString(name));
-    return node?.cast<T>();
+    return node?.as<T>();
   }
 }
 

src/dart/godot_dart_build/lib/src/godot_script_generator.dart

@@ -149,7 +149,6 @@ class GodotScriptAnnotationGenerator
       buffer.writeln('  name: \'$exportName\',');
       buffer.writeln('  dartMethodName: \'${element.name}\',');
     } else if (element.hasOverride) {
-      // TODO - I might change the naming scheme here
       final godotMethodName = _convertVirtualMethodName(element.name);
       buffer.writeln('  name: \'$godotMethodName\',');
       buffer.writeln('  dartMethodName: \'${element.name}\',');
@@ -311,7 +310,7 @@ class GodotScriptAnnotationGenerator
     StringBuffer buffer = StringBuffer();
 
     final className = element.name;
-    final rpcMethodsClass = '_\$${className}RpcMethods';
+    final rpcMethodsClass = '\$${className}RpcMethods';
     buffer.writeln('class $rpcMethodsClass {');
     buffer.writeln('  $className self;');
     buffer.writeln('  $rpcMethodsClass(this.self);');