Event Dispatcher Example

Event-Dispatcher.MD

Usage

$event = new SyncDispatcher;

$event->listen('subscribed', function () {
   echo 'handling it 1' . PHP_EOL;
});

$event->listen('un-subscribed', function () {
    echo 'un-subscribed it 1' . PHP_EOL;
});

$event->listen('subscribed', function () {
    echo 'handling it 2' . PHP_EOL;
});

$event->fire('subscribed');
$event->fire('un-subscribed');

event-dispatcher.php

<?php
 /**
 * Interface EventDispatcher
 */
interface EventDispatcher
{
    /**
     * @param $name
     * @param $handler
     *
     * @return mixed
     */public function listen($name, $handler);

    /**
     * @param $name
     *
     * @return mixed
     */public function fire($name);
    }

    /**
     * Class SyncDispatcher
     */
    class SyncDispatcher implements EventDispatcher
    {
    /**
     * @var array
     */
    protected $events = [];

    /**
     * @param $name
     * @param $handler
     *
     * @return void
     */
    public function listen($name, $handler)
    {
        $this->events[$name][] = $handler;
    }

    /**
     * @param $name
     *
     * @return bool
     */
    public function fire($name)
    {
        if (!array_key_exists($name, $this->events)) {
            return false;
        }

        foreach ($this->events[$name] as $event) {
            $event();
        }
        return true;
    }
}