Yukihiro Matsumoto wrote:

> |I think this would only make sense when combined with a deep clone. It 
> |would be nice to have GC's object graph traversal functionality exposed. 
> |It is a good thing to have something like that available generally.
> |
> |matz, are you listening?
> 
> Yes, I am.  I think it's good to have general purpose object graph
> traverser.  But I'm not going to expose GC marker, for it's tailored
> for garbage collection.

Agreed, the GC already knows how to traverse all the built-in classes 
(not sure if this is bundled to marking) so maybe that could be factored 
out. RData classes would still need to provide a method / callback for 
this in any case so this is still a change that needs pondering. Guess 
it can wait. :)

Thanks for the quick response.