Challenge supporting custom deepcopy with inheritance

[Scott David Daniels]

Michael H. Goldwasser wrote:
> Chris,
> 
>   Thanks for your well-written reply.  Your analogy to the
>   complexities of other special methods is well noted.  I'll accept
>   the "small price for flexibility" that you note, if necessary.
>   However, I still desire a cleaner solution.

You seem to think that "deepcopy" is a well-defined concept.  It is
not and cannot be.  A copy that understands its own abstractions can
work, but sometimes a container is used as a simple abstraction, and
sometimes it is used as a container.  The choice between the two is
not one of structure, but one of intent.  A true deepcopy could
survive making a copy of the number 23, but might fail as it makes
a copy of None, True, or False.  Certainly a dictionary might or
might not be copied, depending on how the dictionary is used.

--Scott David Daniels
Scott.Daniels at Acm.Org