Trait System

core/object/object.cpp

@@ -932,6 +932,7 @@ void Object::set_script(const Variant &p_script) {
 		ERR_FAIL_COND_MSG(s.is_null(), "Cannot set object script. Parameter should be null or a reference to a valid script.");
 		ERR_FAIL_COND_MSG(s->is_abstract(), vformat("Cannot set object script. Script '%s' should not be abstract.", s->get_path()));
 	}
+	ERR_FAIL_COND_MSG(!s->is_attachable(), vformat("Cannot set object script. Script '%s' is not attachable.", s->get_path()));
 
 	script = p_script;
 

core/object/script_language.cpp

@@ -173,6 +173,7 @@ void Script::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("is_tool"), &Script::is_tool);
 	ClassDB::bind_method(D_METHOD("is_abstract"), &Script::is_abstract);
+	ClassDB::bind_method(D_METHOD("is_attachable"), &Script::is_attachable);
 
 	ClassDB::bind_method(D_METHOD("get_rpc_config"), &Script::get_rpc_config);
 

core/object/script_language.h

@@ -166,6 +166,7 @@ class Script : public Resource {
 	virtual bool is_tool() const = 0;
 	virtual bool is_valid() const = 0;
 	virtual bool is_abstract() const = 0;
+	virtual bool is_attachable() const { return true; }
 
 	virtual ScriptLanguage *get_language() const = 0;
 
@@ -214,6 +215,7 @@ class ScriptLanguage : public Object {
 	virtual void init() = 0;
 	virtual String get_type() const = 0;
 	virtual String get_extension() const = 0;
+	virtual bool is_language_script_attachable() const { return true; }
 	virtual void finish() = 0;
 
 	/* EDITOR FUNCTIONS */

doc/classes/Script.xml

@@ -6,7 +6,7 @@
 	<description>
 		A class stored as a resource. A script extends the functionality of all objects that instantiate it.
 		This is the base class for all scripts and should not be used directly. Trying to create a new script with this class will result in an error.
-		The [code]new[/code] method of a script subclass creates a new instance. [method Object.set_script] extends an existing object, if that object's class matches one of the script's base classes.
+		The [code]new[/code] method of a script subclass creates a new instance. [method Object.set_script] extends an existing object, if that object's class matches one of the script's base classes and if script is attachable check by [method is_attachable].
 	</description>
 	<tutorials>
 		<link title="Scripting documentation index">$DOCS_URL/tutorials/scripting/index.html</link>
@@ -115,6 +115,12 @@
 				Returns [code]true[/code] if the script is an abstract script. An abstract script does not have a constructor and cannot be instantiated.
 			</description>
 		</method>
+		<method name="is_attachable" qualifiers="const">
+			<return type="bool" />
+			<description>
+				Returns [code]true[/code] if the script is able to be attached to [Object].
+			</description>
+		</method>
 		<method name="is_tool" qualifiers="const">
 			<return type="bool" />
 			<description>

editor/filesystem_dock.cpp

@@ -4301,6 +4301,7 @@ FileSystemDock::FileSystemDock() {
 	make_scene_dialog->connect(SceneStringName(confirmed), callable_mp(this, &FileSystemDock::_make_scene_confirm));
 
 	make_script_dialog = memnew(ScriptCreateDialog);
+	make_script_dialog->set_languages_list(false);
 	make_script_dialog->set_title(TTR("Create Script"));
 	add_child(make_script_dialog);
 

editor/script_create_dialog.cpp

@@ -128,17 +128,16 @@ void ScriptCreateDialog::_notification(int p_what) {
 		} break;
 
 		case NOTIFICATION_THEME_CHANGED: {
-			for (int i = 0; i < ScriptServer::get_language_count(); i++) {
-				Ref<Texture2D> language_icon = get_editor_theme_icon(ScriptServer::get_language(i)->get_type());
-				if (language_icon.is_valid()) {
-					language_menu->set_item_icon(i, language_icon);
-				}
-			}
+			set_languages_list(is_languages_list_only_attachable);
 
 			path_button->set_icon(get_editor_theme_icon(SNAME("Folder")));
 			parent_browse_button->set_icon(get_editor_theme_icon(SNAME("Folder")));
 			parent_search_button->set_icon(get_editor_theme_icon(SNAME("ClassList")));
 		} break;
+
+		case NOTIFICATION_POSTINITIALIZE: {
+			set_languages_list(is_languages_list_only_attachable);
+		} break;
 	}
 }
 
@@ -194,6 +193,38 @@ void ScriptCreateDialog::set_inheritance_base_type(const String &p_base) {
 	base_type = p_base;
 }
 
+void ScriptCreateDialog::set_languages_list(const bool p_only_attachable) {
+	is_languages_list_only_attachable = p_only_attachable;
+	String previous_default;
+	if (language_menu->get_selected_id() > -1) {
+		previous_default = language_menu->get_item_text(language_menu->get_selected_id());
+	}
+	default_language = -1;
+	language_menu->clear();
+	int skipped_lang = 0;
+	for (int i = 0; i < ScriptServer::get_language_count(); i++) {
+		ScriptLanguage *lang = ScriptServer::get_language(i);
+		if (p_only_attachable && !lang->is_language_script_attachable()) {
+			skipped_lang++;
+			continue;
+		}
+		language_menu->add_item(lang->get_name());
+		Ref<Texture2D> language_icon = get_editor_theme_icon(lang->get_type());
+		if (language_icon.is_valid()) {
+			language_menu->set_item_icon(i - skipped_lang, language_icon);
+		}
+		if (lang->get_name() == previous_default) {
+			default_language = i - skipped_lang;
+		}
+		if (default_language == -1 && lang->get_name() == "GDScript") {
+			default_language = i - skipped_lang;
+		}
+	}
+	if (default_language >= 0) {
+		language_menu->select(default_language);
+	}
+}
+
 bool ScriptCreateDialog::_validate_parent(const String &p_string) {
 	if (p_string.length() == 0) {
 		return false;
@@ -854,18 +885,6 @@ ScriptCreateDialog::ScriptCreateDialog() {
 	gc->add_child(memnew(Label(TTR("Language:"))));
 	gc->add_child(language_menu);
 
-	default_language = -1;
-	for (int i = 0; i < ScriptServer::get_language_count(); i++) {
-		String lang = ScriptServer::get_language(i)->get_name();
-		language_menu->add_item(lang);
-		if (lang == "GDScript") {
-			default_language = i;
-		}
-	}
-	if (default_language >= 0) {
-		language_menu->select(default_language);
-	}
-
 	language_menu->connect(SceneStringName(item_selected), callable_mp(this, &ScriptCreateDialog::_language_changed));
 
 	/* Inherits */

editor/script_create_dialog.h

@@ -68,6 +68,7 @@ class ScriptCreateDialog : public ConfirmationDialog {
 	AcceptDialog *alert = nullptr;
 	CreateDialog *select_class = nullptr;
 
+	bool is_languages_list_only_attachable = true;
 	bool is_browsing_parent = false;
 	String path_error;
 	String template_inactive_message;
@@ -124,6 +125,7 @@ class ScriptCreateDialog : public ConfirmationDialog {
 public:
 	void config(const String &p_base_name, const String &p_base_path, bool p_built_in_enabled = true, bool p_load_enabled = true);
 	void set_inheritance_base_type(const String &p_base);
+	void set_languages_list(const bool p_only_attachable);
 	ScriptCreateDialog();
 };
 

modules/gdscript/.editorconfig

@@ -1,3 +1,7 @@
 [*.gd]
 indent_size = 4
 trim_trailing_whitespace = true
+
+[*.gdt]
+indent_size = 4
+trim_trailing_whitespace = true

modules/gdscript/config.py

@@ -10,7 +10,9 @@ def configure(env):
 def get_doc_classes():
     return [
         "@GDScript",
+        "@GDTrait",
         "GDScript",
+        "GDTrait",
         "GDScriptSyntaxHighlighter",
     ]