system/libraries/Event_Observer.php

   1 <?php defined('SYSPATH') OR die('No direct access allowed.');
   2 /**
   3  * Kohana event observer. Uses the SPL observer pattern.
   4  *
   5  * $Id: Event_Observer.php 3917 2009-01-21 03:06:22Z zombor $
   6  *
   7  * @package    Core
   8  * @author     Kohana Team
   9  * @copyright  (c) 2007-2008 Kohana Team
  10  * @license    http://kohanaphp.com/license.html
  11  */
  12 abstract class Event_Observer implements SplObserver {
  13
  14         // Calling object
  15         protected $caller;
  16
  17         /**
  18          * Initializes a new observer and attaches the subject as the caller.
  19          *
  20          * @param   object  Event_Subject
  21          * @return  void
  22          */
  23         public function __construct(SplSubject $caller)
  24         {
  25                 // Update the caller
  26                 $this->update($caller);
  27         }
  28
  29         /**
  30          * Updates the observer subject with a new caller.
  31          *
  32          * @chainable
  33          * @param   object  Event_Subject
  34          * @return  object
  35          */
  36         public function update(SplSubject $caller)
  37         {
  38                 if ( ! ($caller instanceof Event_Subject))
  39                         throw new Kohana_Exception('event.invalid_subject', get_class($caller), get_class($this));
  40
  41                 // Update the caller
  42                 $this->caller = $caller;
  43
  44                 return $this;
  45         }
  46
  47         /**
  48          * Detaches this observer from the subject.
  49          *
  50          * @chainable
  51          * @return  object
  52          */
  53         public function remove()
  54         {
  55                 // Detach this observer from the caller
  56                 $this->caller->detach($this);
  57
  58                 return $this;
  59         }
  60
  61         /**
  62          * Notify the observer of a new message. This function must be defined in
  63          * all observers and must take exactly one parameter of any type.
  64          *
  65          * @param   mixed   message string, object, or array
  66          * @return  void
  67          */
  68         abstract public function notify($message);
  69
  70 } // End Event Observer