Event_Dispatcher::addObserver PHP Méthode

    public function addObserver($callback, $nName = EVENT_DISPATCHER_GLOBAL, $class = null)
    {
        if (is_array($callback)) {
            if (is_object($callback[0])) {
                // Note : PHP4 does not allow correct object comparison so
                // only the class name is used for registration checks.
                $reg = get_class($callback[0]) . '::' . $callback[1];
            } else {
                $reg = $callback[0] . '::' . $callback[1];
            }
        } else {
            $reg = $callback;
        }
        $this->_ro[$nName][$reg] = array('callback' => $callback, 'class' => $class);
        // Post eventual pending notifications for this observer
        if (isset($this->_pending[$nName])) {
            foreach (array_keys($this->_pending[$nName]) as $k) {
                $notification =& $this->_pending[$nName][$k];
                if (!$notification->isNotificationCancelled()) {
                    $objClass = get_class($notification->getNotificationObject());
                    if (empty($class) || strcasecmp($class, $objClass) == 0) {
                        call_user_func_array($callback, array(&$notification));
                        $notification->increaseNotificationCount();
                    }
                }
            }
        }
    }

 /**
  * For the given plugin, add all the observers of this plugin.
  */
 private function addPluginObservers(Piwik_Plugin $plugin)
 {
     $hooks = $plugin->getListHooksRegistered();
     foreach ($hooks as $hookName => $methodToCall) {
         $this->dispatcher->addObserver(array($plugin, $methodToCall), $hookName);
     }
 }