Comments on: Utility Functions For Classes

By: NoriSte

NoriSte — Mon, 04 Jan 2010 15:41:50 +0000

See @ this code in the document class:

var movieClip : MovieClip = new MovieClip();
var obj : Object = {};
obj.myFunction = function(){};

trace( Object( myFunction ).constructor ); //myFunction is a function of the document class
trace( Object( movieClip.play ).constructor );
trace( Object( obj.myFunction ).constructor );

Flash traces this:
[class MethodClosure]
[class MethodClosure]
[class Function]

By: jackson

jackson — Wed, 30 Dec 2009 18:27:21 +0000

First of all, mine is longer than yours partly because mine includes more features. The try/catch block alone adds several lines, as does the null check. The purpose of these is to catch errors and return null rather than propagating them. I also fall back to getDisplayObjectClass. Other than that, my version is quite short. I'm not striving for performance in these functions as you would typically not use them in a performance-critical area of code. Instead, you would cache their result. Other than that, your constructor field version does seem to work. I'm puzzled though- what is the purpose of your check against [class MethodClosure]? Is MethodClosure a class you've written and would like to treat specially?

By: NoriSte

NoriSte — Wed, 30 Dec 2009 16:21:32 +0000

I use this my own simple function

public function getClass ( obj : * ) : Class
    {
        var con : * = Object( obj ).constructor;
 
        if( con.toString() == "[class MethodClosure]" )
            con = Function;        
 
        return con as Class;
    }

But the your one is longer than mine; I’m here for asking you if I’m loosing anything using my poor-code function… perhaps is slower in performance? (but I haven’t tested, these are only assumptions) or my getClass has some faults? I’ve been used it for a long time and it has caused me no one problem until now :-)

By: jackson

jackson — Wed, 09 Dec 2009 22:06:28 +0000

Good catch! It must have been left over from a previous implementation. I’ve removed it and updated the article. Thanks!

By: dVyper

dVyper — Wed, 09 Dec 2009 09:18:23 +0000

Nice functions :-)

Just a note that it doesn’t seem like you need the “var c:Class;” line in your getClassByName function.

By: jackson

jackson — Mon, 07 Dec 2009 17:35:53 +0000

I too came to the same solution involving a switch, except I went all the way up to 20 parameters. I guess that would be another Class-related utility function.

By: Piergiorgio Niero

Piergiorgio Niero — Mon, 07 Dec 2009 13:08:48 +0000

Yep, AS3 lacks a good set of functions to get information over classes and reflect object.
recently I experimented a bit on reflection and it has been very frustrating not to be able to create a flexible factory without workarounding as3 limitations.

I wrote a post ( http://twurl.nl/omcds2 ) and opened a feature request ( http://twurl.nl/hh84o7 ) to make things easier in next future, let’s hope adobe will reflect on flash :)

my 2 cents,
pigiuz

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Mon, 07 Dec 2009 09:38:18 +0000

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