访问者模式

场景:我们需要在用户积分增加的时候,写入一个日志文件,同时给该用户发送一个邮件.

interface ActionHandle
{
    public function handle(User $user);
}

class User
{
    public $point;
    public $uid;
    public $name;

    public function __construct($point, $uid, $name)
    {
        $this->point = $point;
        $this->uid = $uid;
        $this->name = $name;
    }

    public function addPoint($dValue)
    {
        $this->point += $dValue;
    }

    public function handle(ActionHandle $handle)
    {
        $handle->handle($this);
    }
}

class Log implements ActionHandle
{
    public function handle(User $user)
    {
        file_put_contents(‘log.txt‘, "{$user->uid} {$user->name} 操作积分: 操作后积分{$user->point}");
    }
}

class Email implements ActionHandle
{
    public function handle(User $user)
    {
        $title = "您的积分增加了";
        $content = "{$user->uid} {$user->name} 操作积分: 操作后积分{$user->point}";
        $this->sendEmail($title, $content);
    }

    protected function sendEmail($title, $content)
    {
        // 发送邮件
        echo $title;
        echo $content;
    }
}

$user = new User(500, 1, ‘jack‘);
$user->addPoint(100);

$log = new Log();
$user->handle($log);

$email = new Email();
$user->handle($email);