note 129422 added to functions.first_class_callable_syntax

Using first-class callable syntax is a good way to limit function access in WordPress CMS or other systems which use hook system. <?php class My_Hook_Class { public function __construct() { add_filter( 'body_class', $this->filter_body_class( ... ), 100 ); // Pre 8.1 call syntax. add_filter( 'body_class', array( $this, 'filter_body_class' ), 100 ); // 8.1+ call syntax. } private function filter_body_class( array $classes ): array { $classes[] = 'my-custom-class'; return $classes; } } ?> First call will add the body class, second will throw a TypeError call_user_func_array(): Argument #1 ($callback) must be a valid callback, cannot access protected method My_Hook_Class::filter_body_class() ---- Server IP: 45.112.84.4 Probable Submitter: 80.90.13.131 (proxied: 89.216.19.6) ---- Manual Page -- https://php.net/manual/en/functions.first_class_callable_syntax.php Edit -- https://main.php.net/note/edit/129422 Del: integrated -- https://main.php.net/note/delete/129422/integrated Del: useless -- https://main.php.net/note/delete/129422/useless Del: bad code -- https://main.php.net/note/delete/129422/bad+code Del: spam -- https://main.php.net/note/delete/129422/spam Del: non-english -- https://main.php.net/note/delete/129422/non-english Del: in docs -- https://main.php.net/note/delete/129422/in+docs Del: other reasons-- https://main.php.net/note/delete/129422 Reject -- https://main.php.net/note/reject/129422 Search -- https://main.php.net/manage/user-notes.php