README

Event Dispatching is a common and well-tested mechanism to allow developers to inject logic into an application easily and consistently. This library was developed according to PSR-14 and all interfaces in psr/event-dispatcher were implemented.

You can download this project as follows.

git clone git@github.com:pleets/php-event-dispatcher.git

Usage

Creating Events

An Event is a message produced by an Emitter. It may be any arbitrary PHP object. You can create an event extending the Event class.

use Pleets\EventDispatcher\Event;

class DepositEvent extends Event
{
    public string $text;
    protected string $amount;
    private string $currency = 'USD';

    public function __construct($amount)
    {
        $this->amount = $amount;
        $this->text = 'We are preparing your deposit: '.$this->amount.$this->currency;
    }
}

Creating Listeners

A Listener is any PHP callable that expects to be passed an Event. Zero or more Listeners may be passed the same Event. A Listener MAY enqueue some other asynchronous behavior if it so chooses. You can create a listener extending the Listener class.

use Pleets\EventDispatcher\Event;
use Pleets\EventDispatcher\Listener;

class SendDepositNotification extends Listener
{
    public function handle(Event $event): void
    {
        $event->text = 'Your deposit was done!';
    }
}

Creating Listener Providers and subscribing events

A Listener Provider is responsible for determining what Listeners are relevant for a given Event, but MUST NOT call the Listeners itself. A Listener Provider may specify zero or more relevant Listeners. You can create a listener provider as follows.

$provider = new ListenerProvider();

$deposit = new DepositEvent('127.00');
$provider->subscribe($deposit, new SendDepositNotification());

Dispatching your events

A Dispatcher is a service object that is given an Event object by an Emitter. The Dispatcher is responsible for ensuring that the Event is passed to all relevant Listeners, but MUST defer determining the responsible listeners to a Listener Provider. You can dispatch you events as follows.

$dispatcher = new Dispatcher($provider);
$dispatcher->dispatch($deposit);

All listeners will be informed about this event and will be executed.