Aplication Language Selector plugin for Zend Framework

<?php

class App_LangSelector extends Zend_Controller_Plugin_Abstract {

    public function preDispatch(Zend_Controller_Request_Abstract $request)
    {
        $lang = $request->getParam('lang', '');

        if ($lang !== 'pl' && $lang !== 'en') {
            $request->setParam('lang', 'pl');
        }

        $lang = $request->getParam('lang');
        if ($lang == 'pl') {
            $locale = 'pl_PL';
        } else {
            $locale = 'en_EN';
        }

        $zl = new Zend_Locale();
        $zl->setLocale($locale);
        Zend_Registry::set('Zend_Locale', $zl);

        $translate = new Zend_Translate('ini', APPLICATION_PATH . '/languages/' . $lang . '.ini', $lang);
        Zend_Registry::set('Zend_Form_Translate', $translate);
        Zend_Form::setDefaultTranslator($translate);
    }
}