<?php

interface Account{
	public function hello($str);
}

class Demo implements Account{
	public function __construct(){}
	public function hello($str = ""){
		echo 'Hello: '.$str;
	}
	public function __destruct(){}
}

class Aop
{
    private $instance;

    public function __construct($instance){
        $this->instance = $instance;
    }
    public function __call($method, $argument){
        if(! method_exists($this->instance, $method)){
            throw new Exception('Undefine function: ' . $method);
        }

        /* 此處加入before代碼 */

        $callBack = array($this->instance, $method);
        $return = call_user_func_array($callBack, $argument);

        /* 此處加入after代碼 */

        return $return;
	}
}

class Factory
{
	public function __construct(){}
    public function getInstance(){
        return new Aop(new Demo());
    }
}

try
{
    $factory = Factory::getInstance();
	$factory->hello('world');
}
catch(Exception $e)
{
    echo 'Caught exception: ',  $e->getMessage();
}