<?php

echo "Observer-Beispiel:<br/><br/>";

$twitter=new SocialNetworkClient();
$facebook=new SocialNetworkClient();

$news=new News();

$news->addObserver($twitter);
$news->addObserver($facebook);

$news->setNeuesteNachricht("Jetzt neu: Produkt X lieferbar!");

class News
{	
	private $neuesteNachricht;
	private $observers=array();
	
	function setNeuesteNachricht($nachricht)
	{
		$this->neuesteNachricht=$nachricht;
		$this->notifyObservers();
	}
	function getNeuesteNachricht()
	{
		return $this->neuesteNachricht;
	}
			
	public function addObserver($observer)
	{
		$this->observers[]=$observer;	
	}
	
	private function notifyObservers()
	{
		foreach($this->observers as $observer) 
		{ 
			$observer->notify($this); 
		} 
	}
	
}

class SocialNetworkClient
{
	//...
	
	public function notify(News $news)
	{
		echo "<div>Neue Nachricht in News: ";
		echo $news->getNeuesteNachricht();
		echo "</div>";			
	}
}