AS3 migration, display list strategy questions..

I addition to quite comprehensive post of dmennenoh's,I would like to point out that the following approach:

_level0.login_mc.login_com

is a very inefficient in both AS3 and AS2 at best. Chasing children from several levels up (as well as parents) is extremely tedious and offers little flexibility. Application architecture (not display list content) that requires this kind of drill down should be revised.

Display list model in AS3 is well structures. It doesn't have holes and has no negative depth indexes. Finding objects on display list is as easy as looping through an array.

AS3 offers huge array of ways to reference objects anywhere in the application. This includes wide usage of events.

>>Should I expect to have needed to make a class variable ahead of time to store a reference to this?

Yes, instead of making a local variable inside a method, make a class variable - then the reference will not be GC'd until you set the variable to null.

So you say:

private  var somepanel:Sprite;

And then in some method:

somePanel = new Sprite();

>>I'm just used to AS2. You just create a movieclip and when the method  ends, the clip still exists and you know the _level0.ref.ref.ref will  always exist and how to get back to it.

AS3 can work much the same. Like you said, doing an addChild on some MovieClip or sprite will negate you from having to keep a reference. Example:

function testClip():void{

  var a:Sprite = new Sprite();

  a.graphics.beginFill(0xFF0000);

  a.graphics.drawRect(0,0,50,50);

  addChild(a);

}

Because the sprite is now on the display list, it won't be garbage collected, even though a was a local variable. There are no levels (thank god) in AS3 but the sprite/clip exists in whatever container you placed it in - running that function on the main timeline and just saying addChild places the sprite on the stage.

>>Lastly I'm so overly used to being able to target a movieclip using a  single daisy chained list of clips, like:  _level0.this_mc.that_mc.those_mc. I noticed I can't seem to do this  approach with the getChild() approach.

Well, you don't really use that approach when you're doing object creation directly with code. You don't need instance names - you just use the reference you got when you created the object. If you need you can keep an array of references. On the other hand if you're building content clips in the IDE for use by your code, then you can reference instance names like you always did. For example say you want to build a simple alert box - so you make a new movie clip. Then you place a dynamic text field inside of, and give it an instance name of theText. In the library you set the dialog clip to export for actionScript and give it a class name of myDialog. In your code then you could do:

var dialog:myDialog = new myDialog();

addChild(dialog);

dialog.theText.text = "Hello World";

Here you can directly reference the myText text field inside the dialog.