pickle complexity limit?

[Paul Rubin]

martin at v.loewis.de (Martin v. Löwis) writes:
> Read the pickle code, understand why it is recursive, and implement an
> alternative that isn't recursive, yet preserves the original semantics
> in terms of pickling order and sequence in which methods are called on
> objects. When you are done, please contribute your changes back, to
> sf.net/projects/python.

I wonder if it's feasible to write a pickler as a C extension that
works something like a pointer-reversing garbage collector,
eliminating the need for recursion and still not needing any extra
storage in the objects.