Fixes #1025: Implemented support for class-level events.

framework/yii/base/Component.php

@@ -358,13 +358,13 @@ class Component extends Object
 	public function hasEventHandlers($name)
 	{
 		$this->ensureBehaviors();
-		return !empty($this->_events[$name]);
+		return !empty($this->_events[$name]) || Event::hasHandlers($this, $name);
 	}
 
 	/**
 	 * Attaches an event handler to an event.
 	 *
-	 * An event handler must be a valid PHP callback. The followings are
+	 * The event handler must be a valid PHP callback. The followings are
 	 * some examples:
 	 *
 	 * ~~~
@@ -374,7 +374,7 @@ class Component extends Object
 	 * 'handleClick'                     // global function handleClick()
 	 * ~~~
 	 *
-	 * An event handler must be defined with the following signature,
+	 * The event handler must be defined with the following signature,
 	 *
 	 * ~~~
 	 * function ($event)
@@ -455,6 +455,7 @@ class Component extends Object
 				}
 			}
 		}
+		Event::trigger($this, $name, $event);
 	}
 
 	/**

framework/yii/base/Event.php

@@ -45,4 +45,136 @@ class Event extends Object
 	 * Note that this varies according to which event handler is currently executing.
 	 */
 	public $data;
+
+	private static $_events = [];
+
+	/**
+	 * Attaches an event handler to a class-level event.
+	 *
+	 * When a class-level event is triggered, event handlers attached
+	 * to that class and all parent classes will be invoked.
+	 *
+	 * For example, the following code attaches an event handler to `ActiveRecord`'s
+	 * `afterInsert` event:
+	 *
+	 * ~~~
+	 * Event::on([ActiveRecord::className, ActiveRecord::EVENT_AFTER_INSERT], function ($event) {
+	 *     Yii::trace(get_class($event->sender) . ' is inserted.');
+	 * });
+	 * ~~~
+	 *
+	 * The handler will be invoked for EVERY successful ActiveRecord insertion.
+	 *
+	 * For more details about how to declare an event handler, please refer to [[Component::on()]].
+	 *
+	 * @param string $class the fully qualified class name to which the event handler needs to attach
+	 * @param string $name the event name
+	 * @param callback $handler the event handler
+	 * @param mixed $data the data to be passed to the event handler when the event is triggered.
+	 * When the event handler is invoked, this data can be accessed via [[Event::data]].
+	 * @see off()
+	 */
+	public static function on($class, $name, $handler, $data = null)
+	{
+		self::$_events[$name][ltrim($class, '\\')][] = [$handler, $data];
+	}
+
+	/**
+	 * Detaches an event handler from a class-level event.
+	 *
+	 * This method is the opposite of [[on()]].
+	 *
+	 * @param string $class the fully qualified class name from which the event handler needs to be detached
+	 * @param string $name the event name
+	 * @param callback $handler the event handler to be removed.
+	 * If it is null, all handlers attached to the named event will be removed.
+	 * @return boolean if a handler is found and detached
+	 * @see on()
+	 */
+	public static function off($class, $name, $handler = null)
+	{
+		$class = ltrim($class, '\\');
+		if (empty(self::$_events[$name][$class])) {
+			return false;
+		}
+		if ($handler === null) {
+			unset(self::$_events[$name][$class]);
+			return true;
+		} else {
+			$removed = false;
+			foreach (self::$_events[$name][$class] as $i => $event) {
+				if ($event[0] === $handler) {
+					unset(self::$_events[$name][$class][$i]);
+					$removed = true;
+				}
+			}
+			if ($removed) {
+				self::$_events[$name][$class] = array_values(self::$_events[$name][$class]);
+			}
+			return $removed;
+		}
+	}
+
+	/**
+	 * Returns a value indicating whether there is any handler attached to the specified class-level event.
+	 * Note that this method will also check all parent classes to see if there is any handler attached
+	 * to the named event.
+	 * @param string|object $class the object or the fully qualified class name specifying the class-level event
+	 * @param string $name the event name
+	 * @return boolean whether there is any handler attached to the event.
+	 */
+	public static function hasHandlers($class, $name)
+	{
+		if (empty(self::$_events[$name])) {
+			return false;
+		}
+		if (is_object($class)) {
+			$class = get_class($class);
+		} else {
+			$class = ltrim($class, '\\');
+		}
+		do {
+			if (!empty(self::$_events[$name][$class])) {
+				return true;
+			}
+		} while (($class = get_parent_class($class)) !== false);
+		return false;
+	}
+
+	/**
+	 * Triggers a class-level event.
+	 * This method will cause invocation of event handlers that are attached to the named event
+	 * for the specified class and all its parent classes.
+	 * @param string|object $class the object or the fully qualified class name specifying the class-level event
+	 * @param string $name the event name
+	 * @param Event $event the event parameter. If not set, a default [[Event]] object will be created.
+	 */
+	public static function trigger($class, $name, $event = null)
+	{
+		if (empty(self::$_events[$name])) {
+			return;
+		}
+		if ($event === null) {
+			$event = new self;
+		}
+		$event->handled = false;
+		$event->name = $name;
+
+		if (is_object($class)) {
+			$class = get_class($class);
+		} else {
+			$class = ltrim($class, '\\');
+		}
+		do {
+			if (!empty(self::$_events[$name][$class])) {
+				foreach (self::$_events[$name][$class] as $handler) {
+					$event->data = $handler[1];
+					call_user_func($handler[0], $event);
+					if ($event instanceof Event && $event->handled) {
+						return;
+					}
+				}
+			}
+		} while (($class = get_parent_class($class)) !== false);
+	}
 }

tests/unit/framework/base/ComponentTest.php

@@ -302,7 +302,6 @@ class ComponentTest extends TestCase
 		$component->detachBehaviors();
 		$this->assertNull($component->getBehavior('a'));
 		$this->assertNull($component->getBehavior('b'));
-
 	}
 }
 

tests/unit/framework/base/EventTest.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ * @link http://www.yiiframework.com/
+ * @copyright Copyright (c) 2008 Yii Software LLC
+ * @license http://www.yiiframework.com/license/
+ */
+
+namespace yiiunit\framework\base;
+
+use yii\base\Component;
+use yii\base\Event;
+use yiiunit\TestCase;
+
+/**
+ * @author Qiang Xue <qiang.xue@gmail.com>
+ * @since 2.0
+ */
+class EventTest extends TestCase
+{
+	public $counter;
+
+	public function setUp()
+	{
+		$this->counter = 0;
+		Event::off(ActiveRecord::className(), 'save');
+		Event::off(Post::className(), 'save');
+		Event::off(User::className(), 'save');
+	}
+
+	public function testOn()
+	{
+		Event::on(Post::className(), 'save', function ($event) {
+			$this->counter += 1;
+		});
+		Event::on(ActiveRecord::className(), 'save', function ($event) {
+			$this->counter += 3;
+		});
+		$this->assertEquals(0, $this->counter);
+		$post = new Post;
+		$post->save();
+		$this->assertEquals(4, $this->counter);
+		$user = new User;
+		$user->save();
+		$this->assertEquals(7, $this->counter);
+	}
+
+	public function testOff()
+	{
+		$handler = function ($event) {
+			$this->counter ++;
+		};
+		$this->assertFalse(Event::hasHandlers(Post::className(), 'save'));
+		Event::on(Post::className(), 'save', $handler);
+		$this->assertTrue(Event::hasHandlers(Post::className(), 'save'));
+		Event::off(Post::className(), 'save', $handler);
+		$this->assertFalse(Event::hasHandlers(Post::className(), 'save'));
+	}
+
+	public function testHasHandlers()
+	{
+		$this->assertFalse(Event::hasHandlers(Post::className(), 'save'));
+		$this->assertFalse(Event::hasHandlers(ActiveRecord::className(), 'save'));
+		Event::on(Post::className(), 'save', function ($event) {
+			$this->counter += 1;
+		});
+		$this->assertTrue(Event::hasHandlers(Post::className(), 'save'));
+		$this->assertFalse(Event::hasHandlers(ActiveRecord::className(), 'save'));
+
+		$this->assertFalse(Event::hasHandlers(User::className(), 'save'));
+		Event::on(ActiveRecord::className(), 'save', function ($event) {
+			$this->counter += 1;
+		});
+		$this->assertTrue(Event::hasHandlers(User::className(), 'save'));
+		$this->assertTrue(Event::hasHandlers(ActiveRecord::className(), 'save'));
+	}
+}
+
+class ActiveRecord extends Component
+{
+	public function save()
+	{
+		$this->trigger('save');
+	}
+}
+
+class Post extends ActiveRecord
+{
+}
+
+class User extends ActiveRecord
+{
+
+}