It sounds like you're thinking that a = null somehow wipes out the object itself. It doesn't. It simply nulls out the variable 'a', which is a different thing from the object that 'a' refers to.

 

Think of variables like 'a' and 'b' as "pointers" to objects. (Technically, they're 4-byte areas of memory that store the memory address where an object exists.) After executing the first two lines, you have two different pointers pointing to the same object. After executing a = null, the 'a' pointer no longer points to the object but the 'b' pointer still does.

 

So now you might be wondering how you wipe out the object itself. You can't do this directly; only the garbage collector can destroy an object. It is allowed to do so whenever there are no references (pointers) to the object. So you could indirectly wipe out your object by setting both 'a' and 'b' to something else. The object would then become eligible for garbage collection at some indefinite time in the future.

 

- Gordon

 

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From: flexcoders@yahoogroups.com [mailto:flexcoders@yahoogroups.com] On Behalf Of Jaime Bermudez
Sent: Tuesday, January 30, 2007 1:52 PM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] AS3 object reference changes?

 

I have a simple question that may be dumb but I find somewhat interesting.  I have something similar to the following simplified AS3 code:

var a:Object = new Object();
var b:Object = a;
             
a = null;

-------------------------------------------

Why does object b hold on to a's object reference?  I would expect b to become null.



Thanks,

Jaime