Event manager based on observer pattern, from this article http://www.cainsvault.com/design-pattern-php-event-dispatcher/

event-manager-based-on-observer-pattern.php

<?php
    interface SubscriberInterface    {
        public static function getSubscribedEvents();
    }

    class BlogSubscriber implements SubscriberInterface {
        public static function getSubscribedEvents() {
            return array(
                'blog_update' => 'Listener'
            );
        }
     
        // The subscribed function
        public function Listener(BlogPublisher $pub) {
            // Write to log
            // $pub->getTitle();
        }
    }
    
    // We also need to extend the event manager to
    // deal with subscribed interfaces.
    class EventManager {
        private $listeners = array();
    
        public function listen($event, $callback) {
            $this->listeners[$event][] = $callback;
        }
    
        public function dispatch($event, PublisherInterface $param) {
            foreach ($this->listeners[$event] as $listener) {
                call_user_func_array($listener, array($param));
            }
        }

        public function addSubscriber(SubscriberInterface $sub) {
            $listeners = $sub->getSubscribedEvents();

            foreach ($listeners as $event => $listener) {
                // Add the subscribed function as an event
                $this->listen($event, array($sub, $listener));
            } 
        }
    }
    
    // How it works
    $event = new EventManager();
    // Create the blog updater
    $blog = new BlogPublisher($event);
    // Register a subscriber, can be anything
    $subscriber = new BlogSubscriber();
    // Add the subscriber
    $event->addSubscriber($subscriber);
    // Update the blog
    $blog->updateBlog();