Keep property values when extending script

(cherry picked from commit 44cf3c22acb140cc2f19f1062c0a4c0a931fd27b)

editor/editor_properties.cpp

@@ -2608,7 +2608,10 @@ void EditorPropertyResource::_resource_selected(const RES &p_resource, bool p_ed
 void EditorPropertyResource::_resource_changed(const RES &p_resource) {
 	// Make visual script the correct type.
 	Ref<Script> s = p_resource;
+	bool is_script = false;
 	if (get_edited_object() && s.is_valid()) {
+		is_script = true;
+		EditorNode::get_singleton()->get_inspector_dock()->store_script_properties(get_edited_object());
 		s->call("set_instance_base_type", get_edited_object()->get_class());
 	}
 
@@ -2634,6 +2637,11 @@ void EditorPropertyResource::_resource_changed(const RES &p_resource) {
 	emit_changed(get_edited_property(), p_resource);
 	update_property();
 
+	if (is_script) {
+		// Restore properties if script was changed.
+		EditorNode::get_singleton()->get_inspector_dock()->apply_script_properties(get_edited_object());
+	}
+
 	// Automatically suggest setting up the path for a ViewportTexture.
 	if (vpt.is_valid() && vpt->get_viewport_path_in_scene().is_empty()) {
 		if (!scene_tree) {

editor/inspector_dock.cpp

@@ -400,6 +400,9 @@ void InspectorDock::_bind_methods() {
 	ClassDB::bind_method("_edit_forward", &InspectorDock::_edit_forward);
 	ClassDB::bind_method("_edit_back", &InspectorDock::_edit_back);
 
+	ClassDB::bind_method("store_script_properties", &InspectorDock::store_script_properties);
+	ClassDB::bind_method("apply_script_properties", &InspectorDock::apply_script_properties);
+
 	ADD_SIGNAL(MethodInfo("request_help"));
 }
 
@@ -527,6 +530,32 @@ EditorPropertyNameProcessor::Style InspectorDock::get_property_name_style() cons
 	return property_name_style;
 }
 
+void InspectorDock::store_script_properties(Object *p_object) {
+	ERR_FAIL_NULL(p_object);
+	ScriptInstance *si = p_object->get_script_instance();
+	if (!si) {
+		return;
+	}
+	si->get_property_state(stored_properties);
+}
+
+void InspectorDock::apply_script_properties(Object *p_object) {
+	ERR_FAIL_NULL(p_object);
+	ScriptInstance *si = p_object->get_script_instance();
+	if (!si) {
+		return;
+	}
+
+	for (List<Pair<StringName, Variant>>::Element *E = stored_properties.front(); E; E = E->next()) {
+		const Pair<StringName, Variant> &p = E->get();
+		Variant current;
+		if (si->get(p.first, current) && current.get_type() == p.second.get_type()) {
+			si->set(p.first, p.second);
+		}
+	}
+	stored_properties.clear();
+}
+
 InspectorDock::InspectorDock(EditorNode *p_editor, EditorData &p_editor_data) {
 	set_name("Inspector");
 	set_theme(p_editor->get_gui_base()->get_theme());

editor/inspector_dock.h

@@ -100,6 +100,7 @@ class InspectorDock : public VBoxContainer {
 	AcceptDialog *warning_dialog;
 
 	EditorPropertyNameProcessor::Style property_name_style;
+	List<Pair<StringName, Variant>> stored_properties;
 
 	void _prepare_menu();
 	void _menu_option(int p_option);
@@ -144,6 +145,9 @@ public:
 
 	EditorPropertyNameProcessor::Style get_property_name_style() const;
 
+	void store_script_properties(Object *p_object);
+	void apply_script_properties(Object *p_object);
+
 	InspectorDock(EditorNode *p_editor, EditorData &p_editor_data);
 	~InspectorDock();
 };

editor/scene_tree_dock.cpp

@@ -2050,16 +2050,24 @@ void SceneTreeDock::_script_created(Ref<Script> p_script) {
 		return;
 	}
 
-	editor_data->get_undo_redo().create_action(TTR("Attach Script"));
+	InspectorDock *inspector_dock = EditorNode::get_singleton()->get_inspector_dock();
+	UndoRedo &undo_redo = editor_data->get_undo_redo();
+
+	undo_redo.create_action(TTR("Attach Script"));
 	for (List<Node *>::Element *E = selected.front(); E; E = E->next()) {
-		Ref<Script> existing = E->get()->get_script();
-		editor_data->get_undo_redo().add_do_method(E->get(), "set_script", p_script.get_ref_ptr());
-		editor_data->get_undo_redo().add_undo_method(E->get(), "set_script", existing);
-		editor_data->get_undo_redo().add_do_method(this, "_update_script_button");
-		editor_data->get_undo_redo().add_undo_method(this, "_update_script_button");
+		Node *node = E->get();
+		Ref<Script> existing = node->get_script();
+		undo_redo.add_do_method(inspector_dock, "store_script_properties", node);
+		undo_redo.add_undo_method(inspector_dock, "store_script_properties", node);
+		undo_redo.add_do_method(node, "set_script", p_script.get_ref_ptr());
+		undo_redo.add_undo_method(node, "set_script", existing);
+		undo_redo.add_do_method(inspector_dock, "apply_script_properties", node);
+		undo_redo.add_undo_method(inspector_dock, "apply_script_properties", node);
+		undo_redo.add_do_method(this, "_update_script_button");
+		undo_redo.add_undo_method(this, "_update_script_button");
 	}
 
-	editor_data->get_undo_redo().commit_action();
+	undo_redo.commit_action();
 
 	_push_item(p_script.operator->());
 	_update_script_button();
@@ -2706,12 +2714,19 @@ void SceneTreeDock::_script_dropped(String p_file, NodePath p_to) {
 	ERR_FAIL_COND(!scr.is_valid());
 	Node *n = get_node(p_to);
 	if (n) {
-		editor_data->get_undo_redo().create_action(TTR("Attach Script"));
-		editor_data->get_undo_redo().add_do_method(n, "set_script", scr);
-		editor_data->get_undo_redo().add_undo_method(n, "set_script", n->get_script());
-		editor_data->get_undo_redo().add_do_method(this, "_update_script_button");
-		editor_data->get_undo_redo().add_undo_method(this, "_update_script_button");
-		editor_data->get_undo_redo().commit_action();
+		InspectorDock *inspector_dock = EditorNode::get_singleton()->get_inspector_dock();
+		UndoRedo &undo_redo = editor_data->get_undo_redo();
+
+		undo_redo.create_action(TTR("Attach Script"));
+		undo_redo.add_do_method(inspector_dock, "store_script_properties", n);
+		undo_redo.add_undo_method(inspector_dock, "store_script_properties", n);
+		undo_redo.add_do_method(n, "set_script", scr);
+		undo_redo.add_undo_method(n, "set_script", n->get_script());
+		undo_redo.add_do_method(inspector_dock, "apply_script_properties", n);
+		undo_redo.add_undo_method(inspector_dock, "apply_script_properties", n);
+		undo_redo.add_do_method(this, "_update_script_button");
+		undo_redo.add_undo_method(this, "_update_script_button");
+		undo_redo.commit_action();
 	}
 }