Codeginter 3 check if class exist

ci3-check-class-exist

public function callexistclass(){
    	$CI = & get_instance();
    	$file_name = 'Test';
        $file_path = APPPATH.'controllers/' . $file_name . '.php';
        $object_name = $file_name;
        if (file_exists($file_path)) {
            require $file_path;
            $CI->$object_name = new $object_name();
            var_dump($CI->$object_name);
        }
        else {
            show_error('Unable to load the requested controller class: ' . $object_name);
        }
    }