Event な書き方

AS3 で自作の Event を使うとき、だいたいこんな感じになる。

ButtonEvent.as

public class ButtonEvent extends Event
{
    public static const CLICKED:String = 'CLICKED';
    public function ButtonEvent(type:String, bubbles:Boolean=false, cancelable:Boolean=false)
    {
        super(type, bubbles, cancelable);
    }
}

Foo.as

public class Button extends EventDispatcher
{
    public function click():void
    {
        dispatchEvent(new ButtonEvent(ButtonEvent.CLICKED));
    }
}

Bar.as

var button:Button = new Button();
button.addEventListener(ButtonEvent.CLICKED, function(e:Event):void {
    trace("The button clicked.");
});

as3signals での書き方

Foo.as

public class Button
{
    public const clicked:Signal = new Signal;
    public function click():void
    {
        clicked.dispatch();
    }
}

Bar.as

var button:Button = new Button();
button.clicked.add(function():void {
    trace("The button clicked.");
});

メリット

ギッハブ→ https://github.com/robertpenner/as3-signals