a message helper with session

MessageHelper.php

<?php
/**
 * Created by PhpStorm.
 * User: Ron
 * Date: 14-6-2
 * Time: 下午5:59
 */

class Zend_View_Helper_MessageHelper{
    /**
     * @var Zend_Session_Namespace
     */
    private $sessionStore;

    public function MessageHelper()
    {
        $this->sessionStore = new Zend_Session_Namespace('message');
        return $this;
    }

    private function show($message,$type)
    {
        $this->sessionStore->message = $message;
        $this->sessionStore->type = $type;
    }

    public function success($message)
    {
        $this->show($message,MessageType::SUCCESS);
    }

    public function error($message)
    {
        $this->show($message,MessageType::ERROR);
    }

    public function warning($message)
    {
        $this->show($message,MessageType::WARNING);
    }

    public function info($message)
    {
        $this->show($message,MessageType::INFO);
    }

    public function listener()
    {
        if(isset($this->sessionStore->message)&&isset($this->sessionStore->type)){
            $message = '<div class="sys-message '.$this->sessionStore->type.'">'.$this->sessionStore->message.'</div>';
            unset($this->sessionStore->message);
            unset($this->sessionStore->type);
            return $message;
        }
    }
}

class MessageType {
    const  ERROR = 'error';
    const  SUCCESS = 'success';
    const  WARNING = 'warning';
    const  INFO = 'info';
}