Re: Emacs design and architecture. How about copy-on-write?

[Richard Stallman]

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  > A value in a value-cell (etc.) would have an associated thread value, the
  > thread which "owns" it.  When thread1 gets cloned from thread0, it
  > continues to use thread0's data state until it writes foo (e.g. by
  > binding it).  This would create a new value/thread pair, foo/thread1.
  > Further writes of foo by thread1 would continue to access foo/thread1.

It sounds reasonable to me.  It might be feasible to implement
as part of the mechanism that handles local values.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)