private function unsetGlobal($var, $type) {
        switch ($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 : " . $type);
                break;
        }
        if (!array_key_exists($var, $global)) {
            return false;
        }
        unset($global[$var]);
        return true;
    }