Mediator use in separate class

call.php

<?php
    $start = microtime();
	require_once '../config/config.php';
	require_once CORE . 'lib/Order/Order.php';
	$class = basename(__FILE__);
	$test = $_GET['test'];

	$order = new Order(2);
	switch ($test) {
			case 'test':
				$data = 'test';
				break;

		    case 'getOrderStatus':
				$data = $order->changeOrderStatus('Unassigned');
				break;

			default:
				$data = 'GET condition not met';
				break;
		}

	include 'req/data.php';

Class.php

<?php 
  class Order
    {
        public $id;

        function __construct($id)
        {
            $this->mediator = new Mediator();
        }
        
           public function changeOrderStatus($status)
        {
            $value = $this->getOrderStatusValue($status);
            $sql['changeOrderStatus'] = 'UPDATE `orders`
                                            SET `order_status` = ?
                                            WHERE `id` = ' . $this->id;
            $sth = $this->dbh->prepare($sql['changeOrderStatus']);
            $sth->execute(array($value));
            $this->mediator->trigger($status, $this->id);
            return;
        }

mediator.php

<?php
    /**
     *  @usage
     *  $mediator = new Mediator;
     *  $mediator->attach('load', function() { echo "Loading"; });
     *  $mediator->attach('stop', function() { echo "Stopping"; });
     *  $mediator->attach('stop', function() { echo "Stopped"; });
     *  $mediator->trigger('load'); // prints "Loading"
     *  $mediator->trigger('stop'); // prints "StoppingStopped"
     */

    class Mediator {
        protected $events = array();

        public function attach($eventName, $callback) {
            if (!isset($this->events[$eventName])) {
                $this->events[$eventName] = array();
            }
            $this->events[$eventName][] = $callback;
        }

        public function trigger($eventName, $data = null) {
            foreach ($this->events[$eventName] as $callback) {
                $callback($eventName, $data);
            }
            $this->log($eventName, $data);
        }

        public function log($value, $params = null){
            trigger_error("Mediator->trigger Event: " . $value . json_encode($params));
        }
    }

mediatorregister.php

<?php
    require_once CORE . 'lib/Mediator/Mediator.php';

    /**
     * @occurances found at SVN Rev #2841
     */

    // Event listener
    $mediator = new Mediator;

    // Methods to be triggered
    $mediator->attach('demo', function(){
            $foo = new Demo();
            $foo->bar('baz');
         });

  $mediator->attach('Unassigned', function(){

        });