Error Resistible Event interface

Tests/DispatcherTest.php

@@ -11,6 +11,7 @@
 use Joomla\Event\EventInterface;
 use Joomla\Event\EventImmutable;
 use Joomla\Event\Priority;
+use Joomla\Event\Tests\Stubs\ErrorResistibleEvent;
 use Joomla\Event\Tests\Stubs\FirstListener;
 use Joomla\Event\Tests\Stubs\SecondListener;
 use Joomla\Event\Tests\Stubs\SomethingListener;
@@ -717,4 +718,51 @@ public function testRemoveSubscriber()
 		$this->assertFalse($this->instance->hasListener([$listener, 'onSomething']));
 		$this->assertFalse($this->instance->hasListener([$listener, 'onAfterSomething']));
 	}
+
+	/**
+	 * @testdox  An error resistible event works as expected the dispatcher
+	 *
+	 * @covers   \Joomla\Event\Dispatcher
+	 * @uses     \Joomla\Event\ErrorResistibleEventInterface
+	 */
+	public function testErrorResistibleEvent()
+	{
+		$this->instance->addListener('onErroredEventTest', function () {
+			throw new \Exception('Event error 1');
+		});
+		$this->instance->addListener('onErroredEventTest', function () {
+			// No error
+		});
+		$this->instance->addListener('onErroredEventTest', function () {
+			throw new \Exception('Event error 2');
+		});
+
+		$errors = [];
+		$event  = new ErrorResistibleEvent('onErroredEventTest', [], function (\Throwable $e) use (&$errors) {
+			$errors[] = $e->getMessage();
+		});
+
+		$this->instance->dispatch('onErroredEventTest', $event);
+
+		$this->assertEquals(2, count($errors), 'The error handler of the event should collect correct amount of errors.');
+	}
+
+    /**
+	 * @testdox  An error resistible event throws an TypeError when error handler not set
+	 *
+	 * @covers   \Joomla\Event\Dispatcher
+	 * @uses     \Joomla\Event\ErrorResistibleEventInterface
+	 */
+	public function testErrorResistibleEventIncorectlyImplemented()
+	{
+		$this->instance->addListener('onErroredEventTest', function () {
+			throw new \Exception('Event error 1');
+		});
+
+		$event = new ErrorResistibleEvent('onErroredEventTest');
+
+		$this->expectException(\TypeError::class);
+
+		$this->instance->dispatch('onErroredEventTest', $event);
+	}
 }

Tests/Stubs/ErrorResistibleEvent.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * @copyright  Copyright (C) 2005 - 2023 Open Source Matters, Inc. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+
+namespace Joomla\Event\Tests\Stubs;
+
+use Joomla\Event\ErrorResistibleEventInterface;
+use Joomla\Event\ErrorResistibleTrait;
+use Joomla\Event\Event;
+
+/**
+ * An error resistible event
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+class ErrorResistibleEvent extends Event implements ErrorResistibleEventInterface
+{
+    use ErrorResistibleTrait;
+
+    /**
+     * Constructor.
+     *
+     * @param   string      $name          The event name.
+     * @param   array       $arguments     The event arguments.
+     * @param   ?callable   $errorHandler  The event arguments.
+     *
+     * @since   @since  __DEPLOY_VERSION__
+     */
+    public function __construct($name, array $arguments = [], callable $errorHandler = null)
+    {
+        parent::__construct($name, $arguments);
+
+        $this->errorHandler = $errorHandler;
+    }
+}

src/Dispatcher.php

@@ -445,7 +445,23 @@ public function dispatch(string $name, ?EventInterface $event = null): EventInte
             $event = $this->getDefaultEvent($name);
         }
 
-        if (isset($this->listeners[$event->getName()])) {
+        if (!isset($this->listeners[$event->getName()])) {
+            return $event;
+        }
+
+        if ($event instanceof ErrorResistibleEventInterface) {
+            foreach ($this->listeners[$event->getName()] as $listener) {
+                if ($event->isStopped()) {
+                    return $event;
+                }
+
+                try {
+                    $listener($event);
+                } catch (\Throwable $e) {
+                    $event->handleError($e);
+                }
+            }
+        } else {
             foreach ($this->listeners[$event->getName()] as $listener) {
                 if ($event->isStopped()) {
                     return $event;

src/ErrorResistibleEventInterface.php

@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * Part of the Joomla Framework Event Package
+ *
+ * @copyright  Copyright (C) 2005 - 2023 Open Source Matters, Inc. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE
+ */
+
+namespace Joomla\Event;
+
+/**
+ * Interface for error resistible events.
+ * Event implementing this interface allows to handle errors of the event listener.
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+interface ErrorResistibleEventInterface
+{
+    /**
+     * Retrieve error handler for the event.
+     *
+     * @return callable
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function getErrorHandler(): callable;
+
+    /**
+     * Handle the error.
+     *
+     * @param   \Throwable   $error  The error instance
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function handleError(\Throwable $error): void;
+}

src/ErrorResistibleTrait.php

@@ -0,0 +1,52 @@
+<?php
+
+/**
+ * Part of the Joomla Framework Event Package
+ *
+ * @copyright  Copyright (C) 2005 - 2023 Open Source Matters, Inc. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE
+ */
+
+namespace Joomla\Event;
+
+/**
+ * Trait with base method for ErrorResistibleEventInterface
+ *
+ * @since  __DEPLOY_VERSION__
+ */
+trait ErrorResistibleTrait
+{
+    /**
+     * Error handler.
+     *
+     * @return callable
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    private $errorHandler;
+
+    /**
+     * Retrieve error handler for the event.
+     *
+     * @return callable
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function getErrorHandler(): callable
+    {
+        return $this->errorHandler;
+    }
+
+    /**
+     * Handle the error.
+     *
+     * @param   \Throwable   $error  The error instance
+     *
+     * @since  __DEPLOY_VERSION__
+     */
+    public function handleError(\Throwable $error): void
+    {
+        $handler = $this->getErrorHandler();
+        $handler($error);
+    }
+}