On Jan 10, 2006, at 4:12 PM, Alan Lovejoy wrote:

> Bryce wrote: "If you're adding an extra header to every single  
> object in
> your image then I'd think about adding it as an instance variable of
> Object."
>
> UndefinedObject is a subclass of Object.  If one adds an instance  
> variable
> to Object, then nil will have an instance variable. It's value will of
> course initially be nil.
>
> What's the transitive closure?

So? The nil instance would just have a pointer to its own object  
header. It's no worse than any other cyclical set of object references.