The SplSubject interface

aiddroid at example dot com (2013-07-02 07:01:56)

/**
* Subject,that who makes news
*/
class Newspaper implements \SplSubject{
private $name;
private $observers = array();
private $content;

public function __construct($name) {
$this->name = $name;
}
//add observer
public function attach(\SplObserver $observer) {
$this->observers[] = $observer;
}

//remove observer
public function detach(\SplObserver $observer) {

$key = array_search($observer,$this->observers, true);
if($key){
unset($this->observers[$key]);
}
}

//set breakouts news
public function breakOutNews($content) {
$this->content = $content;
$this->notify();
}

public function getContent() {
return $this->content." (by {$this->name})";
}

//notify observers(or some of them)
public function notify() {
foreach ($this->observers as $value) {
$value->update($this);
}
}
}
/**
* Observer,that who recieves news
*/
class Reader implements SplObserver{
private $name;

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

public function update(\SplSubject $subject) {
echo $this->name.' is reading breakout news <b>'.$subject->getContent().'</b><br>';
}
}
//classes test
$newspaper = new Newspaper('Newyork Times');
$allen = new Reader('Allen');
$jim = new Reader('Jim');
$linda = new Reader('Linda');
//add reader
$newspaper->attach($allen);
$newspaper->attach($jim);
$newspaper->attach($linda);
//remove reader
$newspaper->detach($linda);
//set break outs
$newspaper->breakOutNews('USA break down!');
//=========output==========
//Allen is reading breakout news USA break down! (by Newyork Times)
//Jim is reading breakout news USA break down! (by Newyork Times)

Anonymous (2013-05-07 10:37:44)

<?php
class Observable implements SplSubject
{
    private $storage;

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

    function attach(SplObserver $observer)
    {
        $this->storage->attach($observer);
    }

    function detach(SplObserver $observer)
    {
        $this->storage->detach($observer);
    }

    function notify()
    {
        foreach ($this->storage as $obj) {
            $obj->update($this);
        }
    }
    //...
}

abstract class Observer implements SplObserver
{
    private $observable;

    function __construct(Observable $observable)
    {
        $this->observable = $observable;
        $observable->attach($this);
    }

    function update(SplSubject $subject)
    {
        if ($subject === $this->observable) {
            $this->doUpdate($subject);
        }
    }

    abstract function doUpdate(Observable $observable);
}

class ConcreteObserver extends Observer
{
    function doUpdate(Observable $observable)
    {
        //...
    }
}

$observable = new Observable();
new ConcreteObserver($observable);

przemyslaw dot szpiler at gmail dot com (2012-02-26 21:54:34)

<?php 

// Example implementation of Observer design pattern:

class MyObserver1 implements SplObserver {
    public function update(SplSubject $subject) {
        echo __CLASS__ . ' - ' . $subject->getName();
    }
}

class MyObserver2 implements SplObserver {
    public function update(SplSubject $subject) {
        echo __CLASS__ . ' - ' . $subject->getName();
    }
}

class MySubject implements SplSubject {
    private $_observers;
    private $_name;

    public function __construct($name) {
        $this->_observers = new SplObjectStorage();
        $this->_name = $name;
    }

    public function attach(SplObserver $observer) {
        $this->_observers->attach($observer);
    }

    public function detach(SplObserver $observer) {
        $this->_observers->detach($observer);
    }

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

    public function getName() {
        return $this->_name;
    }
}

$observer1 = new MyObserver1();
$observer2 = new MyObserver2();

$subject = new MySubject("test");

$subject->attach($observer1);
$subject->attach($observer2);
$subject->notify();

/* 
will output:

MyObserver1 - test
MyObserver2 - test
*/

$subject->detach($observer2);
$subject->notify();

/* 
will output:

MyObserver1 - test
*/

?>