public function url($controller, $action, $param)
    {
        $path = url();
        if (empty($param)) {
            // return PATH_APP_REL.'/'.$controller.'/'.$action;
            return $path . '/' . $controller.'/'.$action;
        } else {
            // return PATH_APP_REL.'/'.$controller.'/'.$action.'?'.http_build_query($param);
            return $path . '/' . $controller.'/'.$action.'?'.http_build_query($param);
        }
    }