Comments on: getDefinitionByName trick

By: jwopitz

jwopitz — Fri, 21 Aug 2009 18:07:22 +0000

Found this little trick that utilizes a metadata tag that compiles in classes for use with getDefinitionByName

http://www.rozengain.com/blog/2009/08/21/getdefinitionbyname-referenceerror-and-the-frame-metadata-tag/

By: ben

ben — Tue, 04 Aug 2009 16:00:15 +0000

If I understand this correctly, we no longer have to import the to be created class in the creating class, only in the to be created class do we register it as an alias.

So if we have A that we need to instantiate with getDefinitionByName(‘A’) and we do not want to import A, then in the definition of A we registerClassAlias(‘A’, A). Thereby we can use getDefinitionByName(‘A’) anywhere without first importing it.

As far as I can tell, by using registerAlias, we are including the class in the running SWF, which only needs to happen once to be able to use getDefinitionByName.

Hmm but this does bring up an interesting cat and mouse problem. If we need to first instantiate A to call registerAlias, then it would have already been imported, in which case we needn’t have registered it, because the class would need to be imported, loaded into the SWF, and instantiated somewhere for registerAlias to be called.

By: heyitsleo

heyitsleo — Sun, 02 Aug 2009 07:17:32 +0000

Guys I figured out the perfect solution for my specific problem but I have a feeling you can tweak your code to behave in a similar way.
var classNames:Array = [ClassA, ClassB, ClassC]; var classInstances:Object = {}; for each (className:Class in classNames) { classInstances.push(new className()); }
Hope that helps

By: lqdice

lqdice — Sun, 21 Jun 2009 17:41:18 +0000

I don’t quite understand how this works. You’re still pretty much explicitly defining the class you want to import. How is this any less work than doing the

Box;

trick ?

By: sideDoor

sideDoor — Sat, 16 May 2009 21:20:24 +0000

Hello,

As you describe above, I’ve tried using registerClassAlias to assign a static variable in the class definition AS3 (not Flex), and I still get the error:

ReferenceError: Error #1065: Variable MyClass is not defined.

Having applied your method above, I was trying to do something like this:

var dynClass:Class = Class(getDefinitionByName(“fully.qualified.MyClass”));
var dynObj = new dynClass();
addChild(dynObj);

Could you show a usage example? Thanks

By: jivita

jivita — Mon, 02 Mar 2009 00:31:31 +0000

hi,

i tried this in flash and it didn’t work.
i think it is the same problem like embedding somezhing with the [Embed()]

By: Ptest

Ptest — Thu, 19 Feb 2009 23:05:32 +0000

Can someone give me a quick example of a no-frills way to call it? Using the initial NestedObject – quick and dirty on the timeline I’ve tried..

import vo.*;
import flash.utils.getDefinitionByName;
//var uselessArray:Array =[NestedObject];

var Klass:Class = getDefinitionByName(“vo.NestedObject”) as
Class;

// trace(getIt);
new Klass();

the only way it works is if I uncoment the
uselessArray part

Am I going about calling this class correctly?
thanks -

By: jwopitz

jwopitz — Thu, 19 Feb 2009 21:19:01 +0000

Have you tried it in flash? The metadata tags, registerClass and getDefinitionByName are all basic as3, irrespective of your use of Flex. I have not tried it myself in Flash but I would assume it works in Flash as it does in Flex.

By: Ptest

Ptest — Thu, 19 Feb 2009 19:51:13 +0000

The project I’m building is not in Flex so
I would really like to know if there is a way to accomplish this with just Flash (NOT flex).

I use class names passed from an XML doc and use getDefinitionByName to use the strings as classes.

So far I’ve created an (unused) array of all of the potential classes used which works but is really annoying ..

If there is a way to use the registerClass trick with Flash can someone please let us know?

By: bone

bone — Thu, 01 Jan 2009 10:51:22 +0000

Apparently, this code only work if you compile your swf with Flex, due to the [ ] syntax ([RemoteClass(alias="vo.NestedObject")])…

If you compile the swf with the flash IDE, the [ ] call should’nt be considered.

I had the same problem when I was trying to include fonts to the swf, without creating them in the library, but using the [] syntax, as described in the Colin Mook’s AS3 Book.

Could anyone confirm or cancel this assumption?

For those who can’t make the code working, are you devlopping with the Flash IDE?

For those who can get the code working, are you devlopping with the flex builder/sdk?

So far, the solution should be the found of a way to replace the [] call with an Flash IDE’s compiling option (if it exists!)…

Does anybody know something about that?