![Avris Dispatcher](https://avris.it/image/avris-dispatcher_mini.png)
An event dispatcher
Instalation
composer require avris/dispatcher
Event Definition
An event is an object that extends Avris\Dispatcher\Event
.
It has to provide its name (used as an identifier for triggering it)
and a setter and getter for its value (for instance if RequestEvent
is supposed to produce a Response
, that response is the value).
For example:
final class RequestEvent extends Event
{
/** @var RequestInterface */
private $request;
/** @var ResponseInterface */
private $response;
public function __construct(RequestInterface $request)
{
$this->request = $request;
}
public function getName(): string
{
return 'request';
}
public function getRequest(): RequestInterface
{
return $this->request;
}
public function getResponse(): ?ResponseInterface
{
return $this->response;
}
public function setResponse(ResponseInterface $response): self
{
$this->response = $response;
return $this;
}
public function setValue($value): Event
{
$this->response = $value;
return $this;
}
public function getValue()
{
return $this->response;
}
}
Attaching listeners
$dispatcher = new EventDispatcher();
$dispatcher->attachListener(’request’, function (RequestEvent $event) {
if (substr($event->getRequest()->getUrl(), 0, 6) === ‘/admin’ && !is_admin()) {
return new Response(’Forbidden’, 403);
}
});
Returning anything other than null
will automatically set event’s value
(you can also do it explicitly with $event->setResponse($response)
).
As a last argument of attachListener
you can specify the priority of the listener, for example:
$dispatcher->attachListener(’request’, [$this, ‘one’]);
$dispatcher->attachListener(’request’, [$this, ‘two’]);
$dispatcher->attachListener(’request’, [$this, ‘three’], -9);
$dispatcher->attachListener(’request’, [$this, ‘four’], 9);
The listeners will be triggered in order: four
, one
, two
, three
.
To stop propagation of an event, use $event->stopPropagation()
.
Triggering events
To trigger an event:
$response = $dispatcher->trigger(new RequestEvent($request));
As you can see, the value of the event after executing the listeners will be returned for convenience
(again, you can explicitly use $event->getResponse()
).
Event subscribers
A subscriber is an object that defines event listeners in an elegant manner, encapsulating possibly multiple listeners related to one service.
It needs to implement Avris\Dispatcher\EventSubscriberInterface
:
final class FooService implements EventSubscriberInterface
{
public function getSubscribedEvents(): iterable
{
yield ‘request’ => [$this, ‘onRequest’];
yield ‘response:9’ => [$this, ‘onResponse’]; // priority 9
}
}
To register them in the dispatcher:
$fooService = new FooService();
$this->dispatcher->registerSubscriber($fooService);