Re: [Emacs-diffs] scratch/widen-less a4ba846: Replace prog-widen with consolidating widen calls

[Tom Tromey <tom@tromey.com>]

>>>>> "Stefan" == Stefan Monnier <monnier@iro.umontreal.ca> writes:

Stefan> Right.  And use of narrowing is the way that makes this adaption
Stefan> simplest (in many cases it becomes trivial.  See for example how easy
Stefan> it's been to implement mhtml-mode).

It doesn't much matter to me whether narrowing or some other approach is
used.  Narrowing was simpler at the time -- and, I tend to think, will
always be simpler, because the various buffer primitives already respect
it, so you don't need to pass extra information around.  It has the same
sort of utility as dynamic binding in this way, just like RMS pointed
out in that Emacs paper back in the beginning.

However - if something else is more desirable somehow, that's also fine
with me.

Stefan> I don't know of any MMM solution which provides a satisfactory user
Stefan> experience and at the same time works for all major modes,
Stefan> without any need to tweak them at all, no matter how twisted is the
Stefan> major mode's code.

Yes, I completely agree here.  Some changes will be needed.  If you look
through the mhtml development process, there were a few tweaks needed
here and there, at least one of which (a syntax change in sgml mode
IIRC) was quite unexpected.

I haven't really appreciated until recently that maybe some people were
looking for a solution that required no changes.  Better, I think, to
accept that some changes are needed; maybe work to keep the changes
reasonably small and specified; but then just update the interesting
modes (maybe all modes) and move on.

Also, there's still some unanswered questions in mhtml mode.  For
example, the way it captures sub-mode buffer-locals could really be
improved.  Maybe by applying .dir-locals from all the modes; maybe by
having something like the mode hook but for sub-modes -- I'm not sure.

Tom