From: David Vallner <david@...>
Date: 2006-08-27T19:54:34+09:00
Subject: Re: Referencing an object through it's id string.

Ken Bloom wrote:
> On Sun, 27 Aug 2006 12:16:11 +0900, David Vallner wrote:
> 
>> Alexandre Hudelot wrote:
>>> Hello, how does one set a pointer to foo using an id string obtained 
>>> through foo.object_id for instance?
>>>
>>> Thanks in advance
>>>
>> Considering that object ids are only valid throughout one interpreter 
>> run... I'm curious: why pass around the object id instead of the object 
>> itself?
> 
> Have a look at how weakref.rb is implemented. It keeps track of the
> objects it's referencing by object id, because the garbage collector can't
> follow those, but the references can get their objects back
> using ObjectSpace._id2ref (assuming they haven't been garbage collected).

I figured as much, but that was the only behaviour I could think of that 
I'd implement using this. And since it's in the standard library, I'd 
also probably use those weakrefs instead of rolling my own - I'm still 
living in the (naive?) idea that code that gets promoted into standard 
libraries works better than my implementations would.

But then I still wonder. Why pass around object ids instead of weakrefs 
or object references themselves?

David Vallner