Events

Darya\Events

Darya's events package provides a simple implementation of the observer pattern.

• Listeners and dispatchers
• Subscribers

Listeners and dispatchers

The Dispatcher class is Darya's implementation of the Dispatchable interface.

use Darya\Events\Dispatcher;

$dispatcher = new Dispatcher;

Listening to events is as simple as providing an event name and any PHP callable to the listen() method.

$dispatcher->listen('some_event', function ($thing) {
	return "one $thing";
});

$dispatcher->listen('some_event', function ($thing) {
	return "two $thing" . 's';
});

Then, to fire off an event we can use the dispatch() method with an event name and an array of arguments to pass to each listener.

The result of this call will be an array of return values from each listener.

$results = $dispatcher->dispatch('some_event', array('thing')); // array('one thing', 'two things')

To detach a listener, use unlisten().

$dispatcher->unlisten('event', $listener);

Subscribers

Subscribers are objects that listen to multiple events.

They need to implement a public getEventSubscriptions() method from the Subscriber interface, which should return an array with event names for keys and corresponding listeners for values.

use Darya\Events\Subscriber;

class EventSubscriber implements Subscriber
{
	/**
	 * Retrieve the subscriptions.
	 * 
	 * @return array
	 */
	public function getEventSubscriptions()
	{
		return array(
			'event.name'  => [$this, 'listener'],
			'other.event' => function ($argument) {
				return $argument . ' is awesome';
			}
		);
	}
	
	/**
	 * Increment the given value.
	 *
	 * @param mixed $value
	 * @return value
	 */
	public function listener($value)
	{
		return ++$value;
	}
}

We can then give a dispatcher an instance of the subscriber using the subscribe() method.

$subscriber = new EventSubscriber;

$dispatcher->subscribe($susbcriber);

Each listener from the subscriber will then respond when an event is dispatched.

$dispatcher->dispatch('event.name', array(1)); // array(2)
$dispatcher->dispatch('other.event', array('Darya')); // array('Darya is awesome')

And to unsubscribe, just call unsubscribe() with the same reference to the subscriber instance, as you would with single listeners.

$dispatcher->unsubscribe($subscriber);