AS3 - Event listener that only fires once

actionscript-3, addeventlistener, dispatch, events

Solution

I find the cleanest way without using statics or messing up your code with noise is to defining a global function (in a file called removeListenerWhenFired.as) like so:

package your.package
{
    import flash.events.Event;
    import flash.events.IEventDispatcher;

    public function removeListenerWhenFired(callback:Function, useCapture:Boolean = false):Function
    {
        return function (event:Event):void
        {
            var eventDispatcher:IEventDispatcher = IEventDispatcher(event.target)
            eventDispatcher.removeEventListener(event.type, arguments.callee, useCapture)
            callback(event)
        }
    }
}

Then you can listen for events like so:

import your.package.removeListenerWhenFired

// ... class definition

    sprite.addEventListener(MouseEvent.CLICKED, 
        removeListenerWhenFired(
            function (event:MouseEvent):void {
                ... do something
            }
        )
    )

Problem

I'm looking for a way to add an EventListener which will automatically removes itself after the first time it fires, but I can't figure a way of doing this the way I want to. I found this function (here) : ``` public class EventUtil { public static function addOnceEventListener(dispatcher:IEventDispatcher,eventType:String,listener:Function):void { var f:Function = function(e:Event):void { dispatcher.removeEventListener(eventType,f); listener(e); } dispatcher.addEventListener(eventType,f); } } ``` But instead of having to write : ``` EventUtil.addOnceEventListener( dispatcher, eventType, listener ); ``` I would like to use it the usual way : ``` dispatcher.addOnceEventListener( eventType, listener ); ``` Has anybody got an idea of how this could be done? Any help would be greatly apprecitated. (I know that Robert Penner's Signals can do this, but I can't use them since it would mean a lot of code rewriting that I can't afford for my current project)

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