Listen for event in own class?

Question

Hi
I dispatch events from models to classes listening. How do you set up an event and listener in the same class?
Eg for the former - a model "MyModel" to class - it's:
public static const MY_VAR:String = "myVar";
triggered by...
dispatchEvent(new Event(MY_VAR));
picked up in another class by...
modelVar.addEventListener(MyModel.MY_VAR, doSomething);
but what if the class that's dispatching also has the listener?
So if MyClass is dispatching the event, along the lines of...
addEventListener(MyClass.MY_VAR, doSomething);
Cheers for taking a look

Answer 1

Very often I'm waiting for a few key items before I can finally do something else. Setting simple flags or checking nulls can help with this.
Often I download multiple data structures (JSON/XML/etc) and I need all of them before I can parse them because the co-depend on each other. URLLoaders finish at different times so I just set a flag for what I need but check if all are complete before I continue each time one finishes.
e.g.
package
     public class IHateWaiting extends EventDispatcher
          public static const MY_VAR:String = "myVar";
          private var _xmlA:XML;
          private var _xmlB:XML;
          public function IHateWaiting()
               // load A
               var ulA:URLLoader = new URLLoader();
               ulA.addEventListener(Event.COMPLETE, _handleFinishedF);
               ulA.load(new URLRequest("http://www.example.com/a.xml"));
               // load B
               var ulB:URLLoader = new URLLoader();
               ulB.addEventListener(Event.COMPLETE, _handleFinishedF);
               ulB.load(new URLRequest("http://www.example.com/b.xml"));
               // listen to self
               addEventListener(IHateWaiting.MY_VAR, _handleAppEventF);
          private function _handleFinishedF(e:Event):void
               if (e.type == Event.COMPLETE)
                    var data:XML = XML(e.target.data);
                    // A or B? any way you can tell
                    if (data.A.length() > 0) _xmlA = data;
                    else if (data.B.length() > 0) _xmlB = data;
                    // event method (requires extra handler or a fake event)
                    if (_xmlA && _xmlB) dispatchEvent(new Event(IHateWaiting.MY_VAR));
                    // preferred direct reference, no handler needed
                    // if (_xmlA && _xmlB) _parseXML();
          private function _handleAppEventF(e:Event):void
               if (e.type == IHateWaiting.MY_VAR) _parseXML();
          private function _parseXML():void
                // parse XML
I recommend the reference version from post #2. It's cleaner because you don't need to double up on functions (handler->reference) like you see above with dispatching. The only purpose for _handleAppEventF() in this case is just to run _parseXML(), which is a useless duplicate function.
I've always kept my handlers free of model-esque logic, so you see me calling a different function from that handler, _parseXML(). This is just because I want my handlers to only handle events and then hand off the work elsewhere.
Instead of dispatching the event, I agree with moccamaximum, run the method directly. Even if it's 2 lines of code to do 1 thing, I think the clarity of it is much cleaner coding. So I would recommend nuking the self-listener in the constructor above. When I have all the data I'm looking for, I'd run the methods in the class directly and If the parent needs to know, I'd dispatch when they complete.
e.g.
          private function _handleFinishedF(e:Event):void
               if (e.type == Event.COMPLETE)
                    var data:XML = XML(e.target.data);
                    // A or B? any way you can tell
                    if (data.A.length() > 0) _xmlA = data;
                    else if (data.B.length() > 0) _xmlB = data;
                    if (_xmlA && _xmlB)
                         // parse first (synchronous)
                         _parseXML();
                         // xml ready, dispatch to parent
                         dispatchEvent(new Event(IHateWaiting.MY_VAR));