feature #30691 [Contracts][EventDispatcher] add EventDispatcherInterface to symfony/contracts and use it where possible (nicolas-grekas)

This PR was merged into the 4.3-dev branch.

Discussion
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[Contracts][EventDispatcher] add EventDispatcherInterface to symfony/contracts and use it where possible

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This PR adds a new `EventDispatcherInterface` in `Contracts`. This interface contains only one method: `dispatch($event, $eventName)`. That covers almost all use cases of the event dispatcher in components (some use add/removeListeners/Subscribers but they are a minority.)

While doing so, it allows dispatching any objects as events - not only instances of `Event`.

This allows decoupling e.g. `Messenger` from the `EventDispatcher` component.
Next steps could be about planning to remove the base `Event` class from some concrete event classes and/or moving `EventSubscriberInterface` to `symfony/contracts`. It would allow decoupling e.g. `Workflow` from the component - but that's too far away for now, let's think about it in 5.1.

Commits
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3c3db2f14a [Contracts][EventDispatcher] add EventDispatcherInterface to symfony/contracts and use it where possible

Author: fabpot

Command/ConsumeMessagesCommand.php

@@ -20,12 +20,12 @@
 use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Style\SymfonyStyle;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Messenger\RoutableMessageBus;
 use Symfony\Component\Messenger\Transport\Receiver\StopWhenMemoryUsageIsExceededReceiver;
 use Symfony\Component\Messenger\Transport\Receiver\StopWhenMessageCountIsExceededReceiver;
 use Symfony\Component\Messenger\Transport\Receiver\StopWhenTimeLimitIsReachedReceiver;
 use Symfony\Component\Messenger\Worker;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
  * @author Samuel Roze <samuel.roze@gmail.com>

Event/AbstractWorkerMessageEvent.php

@@ -11,13 +11,12 @@
 
 namespace Symfony\Component\Messenger\Event;
 
-use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\Messenger\Envelope;
 
 /**
  * @experimental in 4.3
  */
-abstract class AbstractWorkerMessageEvent extends Event
+abstract class AbstractWorkerMessageEvent
 {
     private $envelope;
     private $receiverName;

Event/SendMessageToTransportsEvent.php

@@ -11,7 +11,6 @@
 
 namespace Symfony\Component\Messenger\Event;
 
-use Symfony\Component\EventDispatcher\Event;
 use Symfony\Component\Messenger\Envelope;
 
 /**
@@ -25,7 +24,7 @@
  *
  * @author Ryan Weaver <ryan@symfonycasts.com>
  */
-class SendMessageToTransportsEvent extends Event
+class SendMessageToTransportsEvent
 {
     private $envelope;
 

Middleware/SendMessageMiddleware.php

@@ -13,13 +13,13 @@
 
 use Psr\Log\LoggerAwareTrait;
 use Psr\Log\NullLogger;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\Event\SendMessageToTransportsEvent;
 use Symfony\Component\Messenger\Stamp\ReceivedStamp;
 use Symfony\Component\Messenger\Stamp\RedeliveryStamp;
 use Symfony\Component\Messenger\Stamp\SentStamp;
 use Symfony\Component\Messenger\Transport\Sender\SendersLocatorInterface;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
  * @author Samuel Roze <samuel.roze@gmail.com>

Tests/Middleware/SendMessageMiddlewareTest.php

@@ -11,7 +11,6 @@
 
 namespace Symfony\Component\Messenger\Tests\Middleware;
 
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\Event\SendMessageToTransportsEvent;
 use Symfony\Component\Messenger\Middleware\SendMessageMiddleware;
@@ -24,6 +23,7 @@
 use Symfony\Component\Messenger\Tests\Fixtures\DummyMessageInterface;
 use Symfony\Component\Messenger\Transport\Sender\SenderInterface;
 use Symfony\Component\Messenger\Transport\Sender\SendersLocator;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 class SendMessageMiddlewareTest extends MiddlewareTestCase
 {

Tests/WorkerTest.php

@@ -12,7 +12,6 @@
 namespace Symfony\Component\Messenger\Tests;
 
 use PHPUnit\Framework\TestCase;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Messenger\Envelope;
 use Symfony\Component\Messenger\Event\WorkerMessageFailedEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageHandledEvent;
@@ -26,6 +25,7 @@
 use Symfony\Component\Messenger\Tests\Fixtures\CallbackReceiver;
 use Symfony\Component\Messenger\Tests\Fixtures\DummyMessage;
 use Symfony\Component\Messenger\Worker;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 class WorkerTest extends TestCase
 {

Worker.php

@@ -12,8 +12,6 @@
 namespace Symfony\Component\Messenger;
 
 use Psr\Log\LoggerInterface;
-use Symfony\Component\EventDispatcher\Event;
-use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Messenger\Event\WorkerMessageFailedEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageHandledEvent;
 use Symfony\Component\Messenger\Event\WorkerMessageReceivedEvent;
@@ -25,6 +23,7 @@
 use Symfony\Component\Messenger\Stamp\RedeliveryStamp;
 use Symfony\Component\Messenger\Stamp\SentStamp;
 use Symfony\Component\Messenger\Transport\Receiver\ReceiverInterface;
+use Symfony\Contracts\EventDispatcher\EventDispatcherInterface;
 
 /**
  * @author Samuel Roze <samuel.roze@gmail.com>
@@ -141,7 +140,7 @@ public function run()
         });
     }
 
-    private function dispatchEvent(Event $event)
+    private function dispatchEvent($event)
     {
         if (null === $this->eventDispatcher) {
             return;