观察者模式

$event = new Event();
$event->addObserver(new Observer1());
$event->addObserver(new Observer2());
$event->trigger();

class Event extends \IMooc\EventGenerator
{
    function trigger()
    {
        echo "Event<br/>\n";

        $this->notify();
    }
}

class Observer1 implements \IMooc\Observer
{
    function update($event_info = null)
    {
        echo "逻辑1<br/>\n";
    }
}

class Observer2 implements \IMooc\Observer
{
    function update($event_info = null)
    {
        echo "逻辑2<br/>\n";
    }
}

<?php
namespace IMooc;

abstract class EventGenerator
{
    private $observers = array();

    function addObserver(Observer $observer)
    {
        $this->observers[] = $observer;
    }

    function notify()
    {
        foreach ($this->observers as $observer)
        {
            $observer->update();
        }
    }
}

<?php
namespace IMooc;

interface Observer
{
    function update($event_info = null);
}