AsEventListener

The "AsEventListener" module enables developers to use the Symfony attribute #[AsEventListener] to register event subscribers/listeners.

To register an event subscriber in Drupal you need to create a service and tag
it as event_subscriber. See Subscribe to and dispatch events on drupal.org.

Symfony however defines the attribute #[AsEventListener] so developers are able to register classes or single methods as event listeners. This module brings this feature to Drupal.
It is planned to add this feature to Drupal core. Until #3376163 is fixed, this module provides a way to make use of it now.

Usage

To make use of this module you need to setup classes or methods as event
listeners using #[AsEventListener]. The classes needs to be in namespace Drupal\[...]\EventListener to be registered automatically.

Example

<?php

namespace Drupal\my_custom_module\EventListener;

#[AsEventListener(event: RoutingEvents::ALTER)]
class TestEventListener {

  /**
   * Use the class directly as event listener.
   *
   * @param \Drupal\Core\Routing\RouteBuildEvent $event
   *   The dispatched event.
   */
  public function __invoke(RouteBuildEvent $event): void {
    // Do something.
  }

}

This will add this class as event listener for RoutingEvents::ALTER so every time this event is dispatched, TestEventListener::__invoke() is called.

See Defining Event Listeners with PHP Attributes for details about how to use #[AsEventListener].