Allow GDExtensions to register virtual methods and call them on scripts

core/extension/gdextension.cpp

@@ -518,6 +518,12 @@ void GDExtension::_register_extension_class_method(GDExtensionClassLibraryPtr p_
 
 	ClassDB::bind_method_custom(class_name, method);
 }
+
+void GDExtension::_register_extension_class_virtual_method(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassVirtualMethodInfo *p_method_info) {
+	StringName class_name = *reinterpret_cast<const StringName *>(p_class_name);
+	ClassDB::add_extension_class_virtual_method(class_name, p_method_info);
+}
+
 void GDExtension::_register_extension_class_integer_constant(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_enum_name, GDExtensionConstStringNamePtr p_constant_name, GDExtensionInt p_constant_value, GDExtensionBool p_is_bitfield) {
 	GDExtension *self = reinterpret_cast<GDExtension *>(p_library);
 
@@ -834,6 +840,7 @@ void GDExtension::initialize_gdextensions() {
 #endif // DISABLE_DEPRECATED
 	register_interface_function("classdb_register_extension_class2", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class2);
 	register_interface_function("classdb_register_extension_class_method", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_method);
+	register_interface_function("classdb_register_extension_class_virtual_method", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_virtual_method);
 	register_interface_function("classdb_register_extension_class_integer_constant", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_integer_constant);
 	register_interface_function("classdb_register_extension_class_property", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property);
 	register_interface_function("classdb_register_extension_class_property_indexed", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property_indexed);

core/extension/gdextension.h

@@ -77,6 +77,7 @@ class GDExtension : public Resource {
 	static void _register_extension_class2(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_parent_class_name, const GDExtensionClassCreationInfo2 *p_extension_funcs);
 	static void _register_extension_class_internal(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_parent_class_name, const GDExtensionClassCreationInfo2 *p_extension_funcs, const ClassCreationDeprecatedInfo *p_deprecated_funcs = nullptr);
 	static void _register_extension_class_method(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassMethodInfo *p_method_info);
+	static void _register_extension_class_virtual_method(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassVirtualMethodInfo *p_method_info);
 	static void _register_extension_class_integer_constant(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_enum_name, GDExtensionConstStringNamePtr p_constant_name, GDExtensionInt p_constant_value, GDExtensionBool p_is_bitfield);
 	static void _register_extension_class_property(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter);
 	static void _register_extension_class_property_indexed(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter, GDExtensionInt p_index);

core/extension/gdextension_interface.cpp

@@ -1194,6 +1194,33 @@ static GDObjectInstanceID gdextension_object_get_instance_id(GDExtensionConstObj
 	return (GDObjectInstanceID)o->get_instance_id();
 }
 
+static GDExtensionBool gdextension_object_has_script_method(GDExtensionConstObjectPtr p_object, GDExtensionConstStringNamePtr p_method) {
+	Object *o = (Object *)p_object;
+	const StringName method = *reinterpret_cast<const StringName *>(p_method);
+
+	ScriptInstance *script_instance = o->get_script_instance();
+	if (script_instance) {
+		return script_instance->has_method(method);
+	}
+	return false;
+}
+
+static void gdextension_object_call_script_method(GDExtensionObjectPtr p_object, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionUninitializedVariantPtr r_return, GDExtensionCallError *r_error) {
+	Object *o = (Object *)p_object;
+	const StringName method = *reinterpret_cast<const StringName *>(p_method);
+	const Variant **args = (const Variant **)p_args;
+
+	Callable::CallError error;
+	memnew_placement(r_return, Variant);
+	*(Variant *)r_return = o->callp(method, args, p_argument_count, error);
+
+	if (r_error) {
+		r_error->error = (GDExtensionCallErrorType)(error.error);
+		r_error->argument = error.argument;
+		r_error->expected = error.expected;
+	}
+}
+
 static GDExtensionObjectPtr gdextension_ref_get_object(GDExtensionConstRefPtr p_ref) {
 	const Ref<RefCounted> *ref = (const Ref<RefCounted> *)p_ref;
 	if (ref == nullptr || ref->is_null()) {
@@ -1515,6 +1542,8 @@ void gdextension_setup_interface() {
 	REGISTER_INTERFACE_FUNC(object_cast_to);
 	REGISTER_INTERFACE_FUNC(object_get_instance_from_id);
 	REGISTER_INTERFACE_FUNC(object_get_instance_id);
+	REGISTER_INTERFACE_FUNC(object_has_script_method);
+	REGISTER_INTERFACE_FUNC(object_call_script_method);
 	REGISTER_INTERFACE_FUNC(ref_get_object);
 	REGISTER_INTERFACE_FUNC(ref_set_object);
 #ifndef DISABLE_DEPRECATED

core/extension/gdextension_interface.h

@@ -364,13 +364,18 @@ typedef struct {
 	GDExtensionClassMethodPtrCall ptrcall_func;
 	uint32_t method_flags; // Bitfield of `GDExtensionClassMethodFlags`.
 
-	/* If `has_return_value` is false, `return_value_info` and `return_value_metadata` are ignored. */
+	/* If `has_return_value` is false, `return_value_info` and `return_value_metadata` are ignored.
+	 *
+	 * @todo Consider dropping `has_return_value` and making the other two properties match `GDExtensionMethodInfo` and `GDExtensionClassVirtualMethod` for consistency in future version of this struct.
+	 */
 	GDExtensionBool has_return_value;
 	GDExtensionPropertyInfo *return_value_info;
 	GDExtensionClassMethodArgumentMetadata return_value_metadata;
 
 	/* Arguments: `arguments_info` and `arguments_metadata` are array of size `argument_count`.
 	 * Name and hint information for the argument can be omitted in release builds. Class name should always be present if it applies.
+	 *
+	 * @todo Consider renaming `arguments_info` to `arguments` for consistency in future version of this struct.
 	 */
 	uint32_t argument_count;
 	GDExtensionPropertyInfo *arguments_info;
@@ -381,6 +386,18 @@ typedef struct {
 	GDExtensionVariantPtr *default_arguments;
 } GDExtensionClassMethodInfo;
 
+typedef struct {
+	GDExtensionStringNamePtr name;
+	uint32_t method_flags; // Bitfield of `GDExtensionClassMethodFlags`.
+
+	GDExtensionPropertyInfo return_value;
+	GDExtensionClassMethodArgumentMetadata return_value_metadata;
+
+	uint32_t argument_count;
+	GDExtensionPropertyInfo *arguments;
+	GDExtensionClassMethodArgumentMetadata *arguments_metadata;
+} GDExtensionClassVirtualMethodInfo;
+
 typedef void (*GDExtensionCallableCustomCall)(void *callable_userdata, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionVariantPtr r_return, GDExtensionCallError *r_error);
 typedef GDExtensionBool (*GDExtensionCallableCustomIsValid)(void *callable_userdata);
 typedef void (*GDExtensionCallableCustomFree)(void *callable_userdata);
@@ -2268,6 +2285,34 @@ typedef GDExtensionObjectPtr (*GDExtensionInterfaceObjectGetInstanceFromId)(GDOb
  */
 typedef GDObjectInstanceID (*GDExtensionInterfaceObjectGetInstanceId)(GDExtensionConstObjectPtr p_object);
 
+/**
+ * @name object_has_script_method
+ * @since 4.3
+ *
+ * Checks if this object has a script with the given method.
+ *
+ * @param p_object A pointer to the Object.
+ * @param p_method A pointer to a StringName identifying the method.
+ *
+ * @returns true if the object has a script and that script has a method with the given name. Returns false if the object has no script.
+ */
+typedef GDExtensionBool (*GDExtensionInterfaceObjectHasScriptMethod)(GDExtensionConstObjectPtr p_object, GDExtensionConstStringNamePtr p_method);
+
+/**
+ * @name object_call_script_method
+ * @since 4.3
+ *
+ * Call the given script method on this object.
+ *
+ * @param p_object A pointer to the Object.
+ * @param p_method A pointer to a StringName identifying the method.
+ * @param p_args A pointer to a C array of Variant.
+ * @param p_argument_count The number of arguments.
+ * @param r_return A pointer a Variant which will be assigned the return value.
+ * @param r_error A pointer the structure which will hold error information.
+ */
+typedef void (*GDExtensionInterfaceObjectCallScriptMethod)(GDExtensionObjectPtr p_object, GDExtensionConstStringNamePtr p_method, const GDExtensionConstVariantPtr *p_args, GDExtensionInt p_argument_count, GDExtensionUninitializedVariantPtr r_return, GDExtensionCallError *r_error);
+
 /* INTERFACE: Reference */
 
 /**
@@ -2483,6 +2528,20 @@ typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClass2)(GDExtensionCl
  */
 typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassMethod)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassMethodInfo *p_method_info);
 
+/**
+ * @name classdb_register_extension_class_virtual_method
+ * @since 4.3
+ *
+ * Registers a virtual method on an extension class in ClassDB, that can be implemented by scripts or other extensions.
+ *
+ * Provided struct can be safely freed once the function returns.
+ *
+ * @param p_library A pointer the library received by the GDExtension's entry point function.
+ * @param p_class_name A pointer to a StringName with the class name.
+ * @param p_method_info A pointer to a GDExtensionClassMethodInfo struct.
+ */
+typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassVirtualMethod)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassVirtualMethodInfo *p_method_info);
+
 /**
  * @name classdb_register_extension_class_integer_constant
  * @since 4.1

core/object/class_db.cpp

@@ -1615,6 +1615,28 @@ void ClassDB::get_virtual_methods(const StringName &p_class, List<MethodInfo> *p
 #endif
 }
 
+void ClassDB::add_extension_class_virtual_method(const StringName &p_class, const GDExtensionClassVirtualMethodInfo *p_method_info) {
+	ERR_FAIL_COND_MSG(!classes.has(p_class), "Request for nonexistent class '" + p_class + "'.");
+
+#ifdef DEBUG_METHODS_ENABLED
+	PackedStringArray arg_names;
+
+	MethodInfo mi;
+	mi.name = *reinterpret_cast<StringName *>(p_method_info->name);
+	mi.return_val = PropertyInfo(p_method_info->return_value);
+	mi.return_val_metadata = p_method_info->return_value_metadata;
+	mi.flags = p_method_info->method_flags;
+	for (int i = 0; i < (int)p_method_info->argument_count; i++) {
+		PropertyInfo arg(p_method_info->arguments[i]);
+		mi.arguments.push_back(arg);
+		mi.arguments_metadata.push_back(p_method_info->arguments_metadata[i]);
+		arg_names.push_back(arg.name);
+	}
+
+	add_virtual_method(p_class, mi, true, arg_names);
+#endif
+}
+
 void ClassDB::set_class_enabled(const StringName &p_class, bool p_enable) {
 	OBJTYPE_WLOCK;
 

core/object/class_db.h

@@ -410,6 +410,7 @@ class ClassDB {
 
 	static void add_virtual_method(const StringName &p_class, const MethodInfo &p_method, bool p_virtual = true, const Vector<String> &p_arg_names = Vector<String>(), bool p_object_core = false);
 	static void get_virtual_methods(const StringName &p_class, List<MethodInfo> *p_methods, bool p_no_inheritance = false);
+	static void add_extension_class_virtual_method(const StringName &p_class, const GDExtensionClassVirtualMethodInfo *p_method_info);
 
 	static void bind_integer_constant(const StringName &p_class, const StringName &p_enum, const StringName &p_name, int64_t p_constant, bool p_is_bitfield = false);
 	static void get_integer_constant_list(const StringName &p_class, List<String> *p_constants, bool p_no_inheritance = false);