AS3 removing event listeners

I have a basic question about manually removing event listeners in actionscript 3.

If I have a function like:

    private function doStuff(event : Event):void
    {

        //let the开发者_如何学JAVAm save
        var f:FileReference = new FileReference();
        f.addEventListener(Event.COMPLETE,saveDone);
        f.save(mp3Encoder.mp3Data,"output.mp3");

    }

How do I remove the event listeners when the saveDone function is called? Normally I just change the "add" to "remove" like:

f.removeEventListener(Event.COMPLETE,saveDone);

However, f is a local variable, and I can't get to it after the doStuff function ends.

    private function saveDone(ev:Event){
        f.removeEventListener(Event.COMPLETE,saveDone);
    }

---

maybe try to reference the original object via the "target" property of the event? I haven't tried it, but something akin to:

private function saveDone(ev:Event){
var originalFR:FileReference = ev.target as FileReference;    
originalFR.removeEventListener(Event.COMPLETE, saveDone);
}

But I may be completely off.

---

A better alternative is to declare the FileReference as a member variable and add the EventHandler in the constructor. You can remove all the EventHandlers in the destructor.

---

It's also a good back-up to add a weak reference so that the listener is removed and garbage collected automatically when there are no references left pointing at it.

f.addEventListener(Event.COMPLETE,saveDone,false,0,true);

However, it's always best to make sure you manually remove a listener.