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<?php class WP_REST_Global_Styles_Controller { public function update_item() { echo "\n" . __METHOD__ . "\n"; $this->prepare_item_for_database(); } protected function prepare_item_for_database() { echo "\n" . __METHOD__ . "\n"; $this->validate_custom_css(); } private function validate_custom_css() { echo __METHOD__ . "()\n"; } } class Gutenberg_REST_Global_Styles_Controller extends WP_REST_Global_Styles_Controller { protected function prepare_item_for_database() { echo "\n" . __METHOD__ . "\n"; $this->validate_custom_css(); } /** * Copy of the parent's method. * The parent's method is private, meaning a child cannot overload or invoke it. * But a child class can have a method with the same name and different visibility. */ protected function validate_custom_css() { echo __METHOD__ . "()\n"; } } class Gutenberg_REST_Global_Styles_Controller_X_X extends Gutenberg_REST_Global_Styles_Controller {} class WP_REST_Global_Styles_Controller_X_X extends WP_REST_Global_Styles_Controller { // will cause a fatal error. protected function prepare_item_for_database() { // overloads the parent's method. echo "\n" . __METHOD__ . "\n"; $this->validate_custom_css(); // will cause a fatal error, as the parent's method is private to it. } } ( new Gutenberg_REST_Global_Styles_Controller() )->update_item(); ( new Gutenberg_REST_Global_Styles_Controller_X_X() )->update_item(); ( new WP_REST_Global_Styles_Controller_X_X() )->update_item();