Subj : Re: Object reference graph: is there a way?
To   : netscape.public.mozilla.jseng
From : anton muhin
Date : Fri Sep 03 2004 08:46 pm

Brendan Eich wrote:
> anton muhin wrote:
> 
>> Dear gurus,
>>
>> Is there a way to find out all the object that directly (or 
>> indirectly) reference the given object with SpiderMonkey's api?
>>
>> Example:
>>
>> var o1 = new Object()
>> var o2 = new Object()
>> var o3 = new Object()
>> var o4 = new Object()
>>
>> o4.foo = o2
>> o4.bar = o3
>>
>> o2.foo = o1
>> o3.bar = o1
>>
>> For o1 I want to know that it is referenced by o2 & o3, and, 
>> indirectly, by o3. I suppose that there could be a way as this issue 
>> seems to be related to garbage collecting.
> 
> Yes, and to uneval/toSource -- try uneval(o1).
I might be missing something or my wording was poor, but uneval seems to 
be wrong tool:

js> var o1 = new Object()
js> var o2 = new Object()
js> o2.foo = o1
[object Object]
js> uneval(o1)
({})
js> uneval(o2)
({foo:{}})
js>

It seems that I cannot find out from o1 that it is referenced by o2.

>> The problem I'm trying to solve is notification on objects modification.
> 
> Why do you want to walk an object graph to notify about modifications?
It's just an event system of VRML JavaScript: I should generate an event 
if a field of an object gets changed. By now we implement standard 
Observer pattern, but I was just curious if we duplicate the mechanism 
that is already present in SpiderMonkey.

Thank you for your time and answers,
with the best regards, anton.

.