PHP中的魔术方法

PHP中有下列称之为魔术方法(magic method)的函数:__construct, __destruct ,
__call, __callStatic,__get, __set, __isset, __unset , __sleep, __wakeup,
__toString, __set_state, __clone and __autoload,本文使用__call为实现一个身份验证的简单实例，代码如下： 代码<?php
    interface Accountable
    {
        const ERR_MSG = "error";
        public function isLoggedIn();
        public function getAccount($user = '');
    }
    abstract class Authentication implements Accountable
    {
        private $account = null;
        public function getAccount($user = '')
        {
            if ($this->account != null) {
                return $this->account;
            } else {
                return ERR_MSG;
            }
        }
        public function isLoggedIn()
        {
            return ($this->account != null);
        }
    }
    class