private function isEmpty($type) {
        switch ($type) {
            case static::GET:
                $global = &$_GET;
                break;
            case static::POST:
                $global = &$this->_getPost();
                break;
            case static::SESSION:
                $global = &$_SESSION;
                break;

            default:
                throw new \Exception("Unknown global type : " . $type);
                break;
        }
        return empty($global);
    }