Removing listeners?

Question

Hi team,
Is it always best practice to remove every listener that you create in a project?
I thought I had this worked out but all of a sudden I am getting errors by trying to use the removed from stage listener.
So there are buttons on the stage and some movieclips that those buttons make visible and here is the code that I am trying to use, but it generates errors on leaving the frame.  I think this is the same as what I have been using but somehow it is now not working for me.
Any help greatly appreciated
cheers
sub
taxb1.visible=false;
taxb2.visible=false;
taxb3.visible=false;
taxb4.visible=false;
taxbn1.addEventListener(MouseEvent.CLICK, taxb1go);
function taxb1go(e:MouseEvent){
          taxb1.visible=true;
taxbn2.addEventListener(MouseEvent.CLICK, taxb2go);
function taxb2go(e:MouseEvent){
          taxb2.visible=true;
taxbn3.addEventListener(MouseEvent.CLICK, taxb3go);
function taxb3go(e:MouseEvent){
          taxb3.visible=true;
taxbn4.addEventListener(MouseEvent.CLICK, taxb4go);
function taxb4go(e:MouseEvent){
          taxb4.visible=true;
taxbn4.addEventListener(Event.REMOVED_FROM_STAGE, taxremoved);
function taxremoved(e:Event){
          taxbn1.removeEventListener(MouseEvent.CLICK, taxb1go);
          taxbn2.removeEventListener(MouseEvent.CLICK, taxb2go);
          taxbn3.removeEventListener(MouseEvent.CLICK, taxb3go);
          taxbn4.removeEventListener(MouseEvent.CLICK, taxb4go);
          taxbn4.removeEventListener(Event.REMOVED_FROM_STAGE, taxremoved);

Answer 1

I don't know what your timeline looks like but I'm assuming you're using it heavily for this.
Gawd you're going to make me go to photoshop. Lets make this real easy and get a picture in here........
Here's an example of not being able to assign a new instance name over 2 frames:
In the above picture the object extends 2 frames. If you clicked on that second frame and changed the instance name, it would change it for frame 1 as well.
Here's 2 keyframes, and an example of where you could set 2 separate instance names:
In the above picture you are making 2 separate instances so therefore you can give each one a different instance name.
That out of the way......
Using the second image example because this is what I assume you are doing, when you go from frame 1 to 2, all your listeners assigned on frame 1 are gone. They will be garbage collected. You do not need to remove them yourself. However if you are programming for a mobile device then it's a good idea to remove them manually anyway to free up ram instantly.
Flash does a lot of things automagically for you. Removing your listeners when you change frames in the second picture is one of them. Setting a weak reference further reinforces that flash is making the right decision to clean up the listeners automatically in garbage collection for you.
Now..
If you REALLY want to remove them yourself, then remove them in the buttons MouseEvent.CLICK method rather than REMOVED_FROM_STAGE. It makes sense and it will always work.
e.g.
btn1.addEventListener(MouseEvent.CLICK, btnHandler, false, 0, true);
function btnHandler(e:MouseEvent):void
     btn1.removeEventListener(MouseEvent.CLICK, btnHandler);  // don't put the extra false, 0, true here or it will error
     gotoAndStop(2);
You get the general idea.. remove 1 - 99999 listeners or whatever you want to do in the CLICK handler, then do what you want the button to do, like move to another frame. You don't need to worry about removing things you have on the timeline from the display list via code. If you use the timeline, the timeline will do that for you.