How to reference the stage object in external actionscript files?

I have an external AS3 class file which is loaded up on the first frame of the Flash movie.

How can I reference the stage object in the AS3 file without having to pass it as a parameter?I mean it seems to me like the stage object is in th开发者_运维百科e global realm - or am I incorrect with this assumption?

Stage is a property of 'stageable' objects: each object derived from DisplayObject, has access to stage:Stage property.

So, Movieclips and Bitmaps have access to the stage property through their ancestor.

A way to "automatically" set the stage property of an object is to add the objects to the display list via addChild().

var mc:MovieClip = new MovieClip();
mc.addEventListener(Event.ADDED_TO_STAGE, func);
trace(mc.stage); //null
addChild(mc);

function func(e:Event){
    mc.stage; //defined, returns reference to the parent since we added it to the display list
}

//this is how to use the listener inside the class
public class Grr extends MovieClip{
     public function Grr(){
         this.addEventListener(Event.ADDED_TO_STAGE, checkF);
     }
     public function checkF(e:Event){
         //inside this function I can do whatever I want that requires stage
     }
}