Dynamic class names are neat

Attaching movieclips to the stage in AS3 is easy. But what if we need to attach a movieclip with dynamically created name?
var page:MovieClip = new ["page"+i]; // won't work :)

But this will:

    var dynamicClass:String = "page" + i;
    var classRef:Class = getDefinitionByName(dynamicClass) as Class;
    var page:MovieClip = new classRef();
    addChild(page);

By seven in flash
4,364 views
28 Comments

Reader comments:

October 6, 2007 @ 14:29

3stripe says:

Interesting…

I usually do it more like this… not sure if it’s the same thing though?

var page:MovieClip = new MovieClip();
page.name = “page”+i;
addChild(page);

October 7, 2007 @ 11:56

seven says:

No no… let’s say you have symbols exported for ActionScript in your Flash CS3 library with the names btn1, btn2, … btnx. And you want to add them to the stage. Then you have to get them out of the library somehow.

This isn’t nor recommended nor book example, I just find this really useful in the case of emergency, cluttered library or my laziness. In many cases I often get design and animations (draft FLA) from designers, and it’s too late for movieclip/symbol reconstruction so I have to work with what I got.

Ok, buttons are lame example. I recently had to add to stage stuff whose linkage id(name) was based on location on the screen. Eg ‘pageTopLeft1′, or ‘pageTopRight8′. I know I could do it completely differently, but sometimes, strict deadlines aren’t helping my AS3 enthusiasm. :)

October 18, 2007 @ 17:04

Og2t says:

Thanks for that, I was looking exactly for it the other day — I had different modules written as AS3 classes and needed to dynamically create instances of them. Eventually, I ended up doing nasty “if” comparsion but your way is much better! Thanks! Greetings from Scotland! :)

October 18, 2007 @ 21:57

seven says:

Scotland! Woot! My as3 nonsense is spreading across the globe! :) Glad I could help.

October 24, 2007 @ 17:25

kam says:

Thanks from Belgium too !
Very useful !!!

May 28, 2008 @ 00:07

Vatrobot says:

Just was I was looking for! (trying to find my as3-workflow somewhere between pure coding and library-usage) Hvala! :)

May 28, 2008 @ 00:13

Vatrobot says:

..for your country collection: Thanx from Germany! :)

June 2, 2008 @ 02:18

xlogic says:

Ok… for your country collection once again, here goes a “thank you from Portugal” :P …

June 16, 2008 @ 16:36

Tim says:

Awesome, cheers for this technique! :D

October 23, 2008 @ 16:42

Goblin says:

Genius! Thank you from Italy (one more for your collection) ;-)

November 15, 2008 @ 17:56

walter says:

Life’s easier, thanks pal.

November 15, 2008 @ 17:57

walter says:

Following this blog’s tradition, thanks from Mexico

December 5, 2008 @ 00:17

Collin says:

Hey thanks for the tip, it works great on Library items, but was wondering how to use it on pure actionscript Classes (like in flex where I don’t have a swf to reference).

All the classes extend Sprite so i’m using that as the base type but get an errorError #1065: Variable InlineEdit is not defined. I’m afraid I have to create an instance of every class I’d like to use before getDefinitionByName will work.

December 18, 2008 @ 18:58

Mars says:

Thanks Man, I have been struggling for this solution over few days.

April 17, 2009 @ 14:05

Polo says:

Again.. thx from canada ^^ !

April 19, 2010 @ 12:48

Alen says:

Thnx from Croatia … ;)

May 20, 2010 @ 21:29

Istvan says:

I think I looked into this some time ago and didn’t find anything on it. So, I was going to go with the “IF …” statements but gave it another try … and found your post. Cool! :D Thanks :)

July 3, 2010 @ 21:43

Tim says:

Dude. I have been looking for this information for 9 months since I started teaching myself AS3 and I finally typed the right search query that brought me to you. THANK YOU THANK YOU THANK YOU!!!!!