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

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> That is _everyone's_ solution, not just yours.  But it is not as easy
> in practice as it may sound.  E.g., imagine a subroutine that is
> called by some higher-level functions, where both the callers and the
> subroutine need to access the same variable.  When other threads are
> running, there's no longer a guarantee that both the caller and the
> callee will see the same value of that variable.  If they must use the
> same value, you now need to pass that variable to the callee via its
> API, and this is not scalable when you have more than a couple,
> especially if the callee is not called directly, but via several
> intermediate callers.

Then the other solution is to establish temporary thread-local bindings
for each of those variables.  I'm not looking forward to the drudgery of
ascertaining precisely which variables warrant such treatment...