passing custom events between modules through parent application

Here's a simple custom event that supports extra data that I use for just about everything:

AppEvent.as:

package {     import flash.events.Event;     public class AppEvent extends Event     {         public static const APP_EVENT:String = "appevent";         public var params:Object;         public function AppEvent(type:String, params:Object, bubbles:Boolean = false, cancelable:Boolean = false)         {             super(type, bubbles, cancelable);             this.params = params;         }         public override function clone():Event         {             return new AppEvent(type, this.params, bubbles, cancelable);         }         public override function toString():String         {             return formatToString("AppEvent", "params", "type", "bubbles", "cancelable");         }     } }

Say I had 2 classes (ClassA and ClassB). If ClassA loads an instance of ClassB inside it, it'd look like this to communicate (doing it by memory, but you get the idea):

ClassA.as:

package {      import flash.display.Sprite;      import AppEvent;      import ClassB;      public class ClassA extends Sprite      {           private var _classB:ClassB = new ClassB();           public function ClassA()           {                addChild(_classB);                // listen for events dispatched in ClassB                _classB.addEventListener(AppEvent.APP_EVENT, _handler);                // How you'd dispatch to ClassB:                // _classB.dispatchEvent(new AppEvent(AppEvent.APP_EVENT, { change:"some data",more:123,data:[1,2,3] }));           }           protected function _handler(e:AppEvent):void           {                // trace what is appended to the params object ("change" from ClassB)                trace("ClassA AppEvent: " + e.params.change);           }      } }

ClassB.as:

package {      import flash.display.Sprite;      import flash.events.Event;      import AppEvent;      // using Sprite here to dispatch events (otherwise would      // need to implement IEventDispatcher.. Sprite is easy      public class ClassB extends Sprite      {           public function ClassB()           {                // how you'd listen for events sent to this class:                // disabled to prevent infinite loops for this example                // addEventListener(AppEvent.APP_EVENT, _handler);                // wait to be added, then dispatch an event                addEventListener(Event.ADDED_TO_STAGE, _init);           }           protected function _init(e:Event):void           {                removeEventListener(Event.ADDED_TO_STAGE, _init);                // now dispatch a custom event, with data                this.dispatchEvent(new AppEvent(AppEvent.APP_EVENT, { change:"This is from ClassB!" }));                // you can name the data whatever you want, I used 'change' for                // no special reason           }           protected function _handler(e:AppEvent):void           {                // trace what is appended to the params object ("change")                trace("ClassB AppEvent: " + e.params.change);           }      } }

Forgive any syntax errors, I typed completely from memory but I think you get the general idea. It's very easy to use events with custom data.

If you made those 3 files, opened a new AS3 document you'd just set it off via:

import flash.events.Event; import ClassA; addEventListener(Event.ENTER_FRAME, init); function init(e:Event):void {      removeEventListener(Event.ENTER_FRAME, init);      var cA:ClassA = new ClassA();      addChild(cA); }