Strategy Design Patter

index.php

<?php

interface Message {

    public function send($event);
}

class Mail implements Message {

    public function send($event)
    {
        var_dump('Sending Mail' . $event);
    }
}

class Pager implements Message {


    public function send($event)
    {
        var_dump('Page Notification' . $event);
    }

}

class Notify {

    public function sendMessage($event, Message $message) {

        $message->send($event);
    }

}

(new Notify())->sendMessage('Server Down', new Pager());

(new Notify())->sendMessage('Server Down', new Mail());