[Feature] Unsubscribe from events.

src/BufferedEventDispatcher.php

@@ -70,4 +70,33 @@ public function subscribeListenersFrom(ListenerSubscriber $subscriber): void
 
         $this->dispatcher->subscribeListenersFrom($subscriber);
     }
+
+
+
+    public function unsubscribeFor(string $event, callable $listener): void
+    {
+        if ( ! $this->dispatcher instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheEventDispatcherIsNotARegistry($this->dispatcher);
+        }
+
+        $this->dispatcher->unsubscribeFor($event, $listener);
+    }
+
+    public function unsubscribeAllFor(string $event): void
+    {
+        if ( ! $this->dispatcher instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheEventDispatcherIsNotARegistry($this->dispatcher);
+        }
+
+        $this->dispatcher->unsubscribeAllFor($event);
+    }
+
+    public function unsubscribeAll(callable $listener): void
+    {
+        if ( ! $this->dispatcher instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheEventDispatcherIsNotARegistry($this->dispatcher);
+        }
+
+        $this->dispatcher->unsubscribeAll($listener);
+    }
 }

src/EventDispatcher.php

@@ -83,4 +83,31 @@ public function subscribeListenersFrom(ListenerSubscriber $subscriber): void
 
         $this->listenerProvider->subscribeListenersFrom($subscriber);
     }
+
+    public function unsubscribeFor(string $event, callable $listener): void
+    {
+        if ( ! $this->listenerProvider instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheListenerProviderIsNotARegistry($this->listenerProvider);
+        }
+
+        $this->listenerProvider->unsubscribeFor($event, $listener);
+    }
+
+    public function unsubscribeAllFor(string $event): void
+    {
+        if ( ! $this->listenerProvider instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheListenerProviderIsNotARegistry($this->listenerProvider);
+        }
+
+        $this->listenerProvider->unsubscribeAllFor($event);
+    }
+
+    public function unsubscribeAll(callable $listener): void
+    {
+        if ( ! $this->listenerProvider instanceof ListenerRegistry) {
+            throw UnableToUnsubscribeListener::becauseTheListenerProviderIsNotARegistry($this->listenerProvider);
+        }
+
+        $this->listenerProvider->unsubscribeAll($listener);
+    }
 }

src/ListenerRegistry.php

@@ -4,6 +4,11 @@
 
 namespace League\Event;
 
+/**
+ * @method void unsubscribeFor(string $event, callable $listener)
+ * @method void unsubscribeAll(callable $listener)
+ * @method void unsubscribeAllFor(string $event)
+ */
 interface ListenerRegistry
 {
     public function subscribeTo(string $event, callable $listener, int $priority = ListenerPriority::NORMAL): void;

src/UnableToUnsubscribeListener.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace League\Event;
+
+use LogicException;
+use Psr\EventDispatcher\EventDispatcherInterface;
+use Psr\EventDispatcher\ListenerProviderInterface;
+
+class UnableToUnsubscribeListener extends LogicException
+{
+    public static function becauseTheListenerProviderIsNotARegistry(
+        ListenerProviderInterface $configuredListenerProvider
+    ): UnableToUnsubscribeListener {
+        $providerClass = get_class($configuredListenerProvider);
+
+        return new UnableToUnsubscribeListener(
+            "Unable to remove listener because the configured listener provider {$providerClass} is not an instance of "
+            . ListenerRegistry::class
+        );
+    }
+    public static function becauseTheEventDispatcherIsNotARegistry(
+        EventDispatcherInterface $configuredListenerProvider
+    ): UnableToUnsubscribeListener {
+        $providerClass = get_class($configuredListenerProvider);
+
+        return new UnableToUnsubscribeListener(
+            "Unable to remove listener because the internal dispatcher {$providerClass} is not an instance of "
+            . ListenerRegistry::class
+        );
+    }
+}