Implementing a global event manager

Author: lorenzo

lib/Cake/Event/CakeEventManager.php

@@ -35,13 +35,51 @@ class CakeEventManager {
  */
 	public static $defaultPriority = 10;
 
+/**
+ * The globally available instance, used for dispatching events attached from any scope
+ *
+ * @var CakeEventManager
+ */
+	protected static $_generalManager = null;
+
 /**
  * List of listener callbacks associated to
  *
  * @var object $Listeners
  */
 	protected $_listeners = array();
 
+/**
+ * Internal flag to distinguish a common manager from the sigleton 
+ *
+ * @var boolean
+ */
+	protected $_isGlobal = false;
+
+
+/**
+ * Returns the globally available instance of a CakeEventManager
+ * this is used for dispatching events attached from outside the scope
+ * other managers were created. Usually for creating hook systems or inter-class
+ * communication
+ *
+ * If called with a first params, it will be set as the globally available instance
+ *
+ * @param CakeEventManager $manager 
+ * @return CakeEventManager the global event manager
+ */
+	public static function instance($manager = null) {
+		if ($manager instanceof CakeEventManager) {
+			self::$_generalManager = $manager;
+		}
+		if (empty(self::$_generalManager)) {
+			self::$_generalManager = new CakeEventManager;
+		}
+
+		self::$_generalManager->_isGlobal = true;
+		return self::$_generalManager;
+	}
+
 /**
  * Adds a new listener to an event. Listeners 
  *
@@ -142,6 +180,11 @@ public function dispatch($event) {
 		if (is_string($event)) {
 			$Event = new CakeEvent($event);
 		}
+
+		if (!$this->_isGlobal) {
+			self::instance()->dispatch($event);
+		}
+
 		if (empty($this->_listeners[$event->name()])) {
 			return;
 		}

lib/Cake/Test/Case/Event/CakeEventManagerTest.php

@@ -273,4 +273,32 @@ public function testDetachSubscriber() {
 		$this->assertEquals(array(), $manager->listeners('fake.event'));
 		$this->assertEquals(array(), $manager->listeners('another.event'));
 	}
+
+/**
+ * Tests that it is possible to get/set the manager singleton
+ *
+ * @return void
+ */
+	public function testGlobalDispatcherGetter() {
+		$this->assertInstanceOf('CakeEventManager', CakeEventManager::instance());
+		$manager = new CakeEventManager;
+
+		CakeEventManager::instance($manager);
+		$this->assertSame($manager, CakeEventManager::instance());
+	}
+
+/**
+ * Tests that the global event manager gets the event too from any other manager
+ *
+ * @return void
+ */
+	public function testDispatchWithGlobal() {
+		$generalManager = $this->getMock('CakeEventManager', array('dispatch'));
+		$manager = new CakeEventManager;
+		$event = new CakeEvent('fake.event');
+		CakeEventManager::instance($generalManager);
+
+		$generalManager->expects($this->once())->method('dispatch')->with($event);
+		$manager->dispatch($event);
+	}
 }