Observer pattern in PHP with SplObjectStrage.

gistfile1.php

<?php
class Subject
{
    private $observers;
    public $message;

    public function __construct()
    {
        $this->observers = new SplObjectStorage();
    }

    public function add_observer(Observer $observer)
    {
        $this->observers->attach($observer);
    }

    public function update($message)
    {
        $this->message = $message;
        foreach ($this->observers as $o) {
            $o->update($this);
        }
    }
}

class Observer
{
    private $name;

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

    public function update(Subject $subject)
    {
        echo "{$this->name} was received message. '{$subject->message}'".PHP_EOL;
    }
}

$o1 = new Observer('observer 1');
$o2 = new Observer('observer 2');

$s = new Subject();
$s->add_observer($o1);
$s->add_observer($o2);
$s->update('shut the fuck up and write some code.');

// observer 1 was received message. 'shut the fuck up and write some code.'
// observer 2 was received message. 'shut the fuck up and write some code.'