Question

When you call a method of a class inside a callback function, you can not use this object.
To call the method, in javascript, I declare that variable, assign this to that, and use that inside the callback to call the method of this.

In actionscript, do I have to do the same way as I do in javascript?

The following code is the example to use that to call a method inside callback.
Are there more simple way in actionscript?

class C {
    private var that:C;

    function C() {
        that = this
    }

    public function f1():void {
        var sp:Sprite = new Sprite;

        sp.addEventListener(MouseEvent.CLICK, function():void {
            this.f2(); // this doesn't work
            that.f2(); // that works
        });
    }

    public function f2():void {
        trace('hello');
    }
}

Answer 1

Here’s another way to do that:

package some.package {
    class SomeSprite extends Sprite {
        public function f1():void
        {
            var sprite1:Sprite = new Sprite;
            sprite1.addEventListener(MouseEvent.CLICK,
                (new Closure(f2, this, ["Hello"], sprite1).handler));

            var sprite2:Sprite = new Sprite;
            sprite2.addEventListener(MouseEvent.CLICK,
                (new Closure(f2, this, ["Bye Bye"], sprite2).handler));
        }

        private function f2(message:String):void
        {
            trace(message);
        }
    }
}

class Closure {
    public var callback:Function;
    public var thisObj:Object;
    public var params:Array;
    public var dispatcher:IEventDispatcher;
    public var cleanAfterCallback:Boolean = true;

    function Closure(callback:Function, thisObj:Object, 
        params:Array, dispatcher:IEventDispatcher)
    {
        this.callback = callback;
        this.thisObj = thisObj;
        this.params = params;
        this.dispatcher = dispatcher;
    }

    public function handler(e:Event):void
    {
        callback.apply(thisObj, params);

        if (cleanAfterCallback)
            dispatcher.removeEventListener(e.type, eventHandler)
    }
}