I think this may help. http://www.helihobby.com/html/alon_desingpattern.html
--- In [email protected], "Shannon" <[EMAIL PROTECTED]> wrote: > > I am new to Cairngorm and Flex (I'm All About Flash) so bear with me. > > I am creating a component and I want it to use Cairngorm. I also want > to be sure that some events fired from the component are only heard > by the Cairngorm of the single component instance. Component > namespaces won't help because I use multiple instances of the same > event, I could probably filter by instance, but I am trying not to > hack (you'll probably see the irony after the next sentence... > > If I use Cairngorm as is... ...and I utilize the Singleton > CairngormEventDispatcher, as soon as I put two instances of a > component on stage, the events from one instance cause the front > controller on the second instance to fire those events > > Sadly this is probably operator error. > > Though I am guessing that someone has had this problem before and > surely there is a best practice solution to this already, I thought I > would spend a little time to explore the issue further and find my > own solution. > > I decided to try to handle this by using separate instances of the > CairngormEventDispatcher (MyViewHelper.dispatcher) for each instance > of my component. Then I could inject that dispatcher into > MyFrontController when it is instantiated so that it knows which > dispatcher to call. > > Just when I think I am on to something, I had to override addCommand > so that it would add an event listener to that instance instead of > the Singleton CairngormEventDispatcher. This is great but it required > two modifications (minor, yet still modifications) to the Cairngorm > FrontController class in order to compile my creation. (see snippets > below) Basically I took two private things and made them protected. > > Of course this might effect other pieces I have yet to build, but my > level of mastery coerces me into believing I have found a solid > answer. <snicker/> If those iteration two guys were really geniuses > they would have made these protected in the first place. > > Ha, ha, ha, just kidding, (I crack myself up) > > So I can either use my own FrontController impl or I can ask the > question: Is this a bug in Cairngorm? Or am I correct in beleiving I > must be doing something wrong... > > Some code samples: > > // > // myViewHelper Snippet: > // > public function MyViewHelper(view:Object) > { > dispatcher = new CairngormEventDispatcher(); > controller = new MyFrontController(dispatcher); > ... > } > > // > // myFrontController Snippet: > // > public class MyFrontController extends FrontController > { > > private var dispatcher:CairngormEventDispatcher; > > public function MyFrontController (dispatcher:CairngormEventDispatcher) > { > super(); > this.dispatcher = dispatcher > ... > } > > public override function addCommand( commandName : String, > commandRef : Class ) : void > { > if( commands[ commandName ] != null ) > { > throw new Error( "Command already registered for " + commandName ); > } > commands[ commandName ] = commandRef; > dispatcher.addEventListener( commandName, executeCommand ); > } > } > > // > // Cairngorm FrontController Mods > // > public class FrontController > { > // ST - 03/15/2007 : private var commands : Dictionary = new > Dictionary(); > protected var commands : Dictionary = new Dictionary(); > > // ST - 03/15/2007 : private function executeCommand( event : > CairngormEvent ) : void > protected function executeCommand( event : CairngormEvent ) : void > > ... > > } >
