Automatically register only engine classes whose header has been included

Author: dsnopek

binding_generator.py

@@ -131,8 +131,6 @@ def get_file_list(api_filepath, output_dir, headers=False, sources=False):
     if sources:
         utility_functions_source_path = source_gen_folder / "variant" / "utility_functions.cpp"
         files.append(str(utility_functions_source_path.as_posix()))
-        register_engine_classes_source_path = source_gen_folder / "register_engine_classes.cpp"
-        files.append(str(register_engine_classes_source_path.as_posix()))
 
     return files
 
@@ -1207,10 +1205,6 @@ def generate_engine_classes_bindings(api, output_dir, use_template_get_node):
                 generate_engine_class_source(class_api, used_classes, fully_used_classes, use_template_get_node)
             )
 
-    register_engine_classes_filename = Path(output_dir) / "src" / "register_engine_classes.cpp"
-    with register_engine_classes_filename.open("w+", encoding="utf-8") as source_file:
-        source_file.write(generate_register_engine_classes_source(api))
-
     for native_struct in api["native_structures"]:
         struct_name = native_struct["name"]
         snake_struct_name = camel_to_snake(struct_name)
@@ -1437,6 +1431,13 @@ def generate_engine_class_header(class_api, used_classes, fully_used_classes, us
     result.append("};")
     result.append("")
 
+    result.append("namespace {")
+    result.append(
+        f"\tinline static ::godot::internal::EngineClassRegistration<{class_name}> _gde_{snake_class_name.lower()}_registration_helper;"
+    )
+    result.append("}")
+    result.append("")
+
     if class_name == "EditorPlugin":
         result.append("class EditorPlugins {")
         result.append("private:")
@@ -1685,38 +1686,6 @@ def generate_engine_class_source(class_api, used_classes, fully_used_classes, us
     return "\n".join(result)
 
 
-def generate_register_engine_classes_source(api):
-    includes = []
-    registrations = []
-
-    for class_api in api["classes"]:
-        if class_api["name"] == "ClassDB":
-            continue
-
-        class_name = class_api["name"]
-        snake_class_name = camel_to_snake(class_name)
-
-        includes.append(f"#include <godot_cpp/classes/{snake_class_name}.hpp>")
-        registrations.append(f"\tClassDB::register_engine_class<{class_name}>();")
-
-    result = []
-    add_header(f"register_engine_classes.cpp", result)
-
-    result.append("#include <godot_cpp/godot.hpp>")
-    result.append("")
-    result = result + includes
-    result.append("")
-    result.append("namespace godot {")
-    result.append("")
-    result.append("void GDExtensionBinding::register_engine_classes() {")
-    result = result + registrations
-    result.append("}")
-    result.append("")
-    result.append("} // namespace godot ")
-
-    return "\n".join(result)
-
-
 def generate_global_constants(api, output_dir):
     include_gen_folder = Path(output_dir) / "include" / "godot_cpp" / "classes"
     source_gen_folder = Path(output_dir) / "src" / "classes"

include/godot_cpp/classes/wrapped.hpp

@@ -111,6 +111,22 @@ namespace internal {
 GDExtensionPropertyInfo *create_c_property_list(const ::godot::List<::godot::PropertyInfo> &plist_cpp, uint32_t *r_size);
 void free_c_property_list(GDExtensionPropertyInfo *plist);
 
+typedef void (*EngineClassRegistrationCallback)();
+void add_engine_class_registration_callback(EngineClassRegistrationCallback p_callback);
+void register_engine_class(const StringName &p_name, const GDExtensionInstanceBindingCallbacks *p_callbacks);
+void register_engine_classes();
+
+template <class T>
+struct EngineClassRegistration {
+	EngineClassRegistration() {
+		add_engine_class_registration_callback(&EngineClassRegistration<T>::callback);
+	}
+
+	static void callback() {
+		register_engine_class(T::get_class_static(), &T::_gde_binding_callbacks);
+	}
+};
+
 } // namespace internal
 
 } // namespace godot

include/godot_cpp/core/class_db.hpp

@@ -119,8 +119,10 @@ class ClassDB {
 	static void register_abstract_class();
 	template <class T>
 	static void register_internal_class();
-	template <class T>
-	static void register_engine_class();
+
+	_FORCE_INLINE_ static void _register_engine_class(const StringName &p_name, const GDExtensionInstanceBindingCallbacks *p_callbacks) {
+		instance_binding_callbacks[p_name] = p_callbacks;
+	}
 
 	template <class N, class M, typename... VarArgs>
 	static MethodBind *bind_method(N p_method_name, M p_method, VarArgs... p_args);
@@ -233,11 +235,6 @@ void ClassDB::register_internal_class() {
 	ClassDB::_register_class<T, false>(false, false);
 }
 
-template <class T>
-void ClassDB::register_engine_class() {
-	instance_binding_callbacks[T::get_class_static()] = &T::_gde_binding_callbacks;
-}
-
 template <class N, class M, typename... VarArgs>
 MethodBind *ClassDB::bind_method(N p_method_name, M p_method, VarArgs... p_args) {
 	Variant args[sizeof...(p_args) + 1] = { p_args..., Variant() }; // +1 makes sure zero sized arrays are also supported.

include/godot_cpp/godot.hpp

@@ -196,9 +196,6 @@ enum ModuleInitializationLevel {
 };
 
 class GDExtensionBinding {
-private:
-	static void register_engine_classes();
-
 public:
 	using Callback = void (*)(ModuleInitializationLevel p_level);
 

src/classes/wrapped.cpp

@@ -28,12 +28,16 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
+#include <unordered_set>
+
 #include <godot_cpp/classes/wrapped.hpp>
 
 #include <godot_cpp/variant/builtin_types.hpp>
 
 #include <godot_cpp/classes/object.hpp>
 
+#include <godot_cpp/core/class_db.hpp>
+
 namespace godot {
 
 const StringName *Wrapped::_get_extension_class_name() const {
@@ -81,6 +85,11 @@ void postinitialize_handler(Wrapped *p_wrapped) {
 
 namespace internal {
 
+std::unordered_set<EngineClassRegistrationCallback> &get_engine_class_registration_callbacks() {
+	static std::unordered_set<EngineClassRegistrationCallback> engine_class_registration_callbacks;
+	return engine_class_registration_callbacks;
+}
+
 GDExtensionPropertyInfo *create_c_property_list(const ::godot::List<::godot::PropertyInfo> &plist_cpp, uint32_t *r_size) {
 	GDExtensionPropertyInfo *plist = nullptr;
 	// Linked list size can be expensive to get so we cache it
@@ -106,6 +115,22 @@ void free_c_property_list(GDExtensionPropertyInfo *plist) {
 	memfree(plist);
 }
 
+void add_engine_class_registration_callback(EngineClassRegistrationCallback p_callback) {
+	get_engine_class_registration_callbacks().insert(p_callback);
+}
+
+void register_engine_class(const StringName &p_name, const GDExtensionInstanceBindingCallbacks *p_callbacks) {
+	ClassDB::_register_engine_class(p_name, p_callbacks);
+}
+
+void register_engine_classes() {
+	std::unordered_set<EngineClassRegistrationCallback> &engine_class_registration_callbacks = get_engine_class_registration_callbacks();
+	for (EngineClassRegistrationCallback cb : engine_class_registration_callbacks) {
+		cb();
+	}
+	engine_class_registration_callbacks.clear();
+}
+
 } // namespace internal
 
 } // namespace godot

src/godot.cpp

@@ -416,7 +416,7 @@ GDExtensionBool GDExtensionBinding::init(GDExtensionInterfaceGetProcAddress p_ge
 	ERR_FAIL_NULL_V_MSG(init_callback, false, "Initialization callback must be defined.");
 
 	Variant::init_bindings();
-	register_engine_classes();
+	godot::internal::register_engine_classes();
 
 	return true;
 }