root/trunk/system/libraries/Event_Subject.php

<?php defined('SYSPATH') or die('No direct script access.');
/**
 * Kohana event subject. Uses the SPL observer pattern.
 *
 * $Id$
 *
 * @package    Core
 * @author     Kohana Team
 * @copyright  (c) 2007-2008 Kohana Team
 * @license    http://kohanaphp.com/license.html
 */
abstract class Event_Subject implements SplSubject {

    // Attached subject listeners
    protected $listeners = array();

    /**
     * Attach an observer to the object.
     *
     * @chainable
     * @param   object  Event_Observer
     * @return  object
     */
    public function attach(SplObserver $obj)
    {
        if ( ! ($obj instanceof Event_Observer))
            throw new Kohana_Exception('eventable.invalid_observer', get_class($obj), get_class($this));

        // Add a new listener
        $this->listeners[spl_object_hash($obj)] = $obj;

        return $this;
    }

    /**
     * Detach an observer from the object.
     *
     * @chainable
     * @param   object  Event_Observer
     * @return  object
     */
    public function detach(SplObserver $obj)
    {
        // Remove the listener
        unset($this->listeners[spl_object_hash($obj)]);

        return $this;
    }

    /**
     * Notify all attached observers of a new message.
     *
     * @chainable
     * @param   mixed   message string, object, or array
     * @return  object
     */
    public function notify($message)
    {
        foreach ($this->listeners as $obj)
        {
            $obj->notify($message);
        }

        return $this;
    }

} // End Event Subject