copy-on-write

[David.Ungar@Eng.Sun.COM (David Ungar)]

I have just skimmed the discussion, but nevertheless am ready to stir
things up!
I would propose that copy-on-write is implementable, but yields an
object model whose strengths and weaknesses are complimentary to
Self's.

Self cleanly separates shared from private information, and
allows for shared state in a straightforward way.

A Lieberman-style system (with copy-on-write) avoids the
non-concrete traits problem but makes it harder to express shared state--
how do you know when NOT to copy-on-write?

Personally, the next language I work on ;-) is going to have a much simpler
model; I suspect both are too complicated.

-- Dave (responsible for many of the overcomplexities in Self and
have learned the hard way) Ungar