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

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: address@hidden
> Date: Mon, 04 Dec 2017 11:49:59 -0500
> 
> > Why does it need to widen, though?
> 
> Because in general, indentation may need to look at the context, and
> that context may be outside of the current user-chosen narrowing.
> 
> > If the mode's indent-line-function is not supposed to call 'widen',
> > why do we do that in indent-according-to-mode?
> 
> We do it in indent-according-to-mode specifically so that
> indent-line-function doesn't need to do it.
> 
> > When you widen, the text that comes into the view will be entirely
> > alien syntactically to the sub-mode that is trying to indent, right?
> 
> The widening is done in indent-according-to-mode and brings into view
> the whole multi-mode buffer, indeed.  Then MMM's indent-line-function is
> called, which narrows the buffer to the relevant chunk and then calls
> the submode's indent-line-function which hence only sees the part of the
> buffer it needs.

Ah, so this assumes that MMM is active in the buffer?  If so, can we
widen only if MMM is indeed active?  Doing so will I believe minimize
(or even eliminate) the effects on existing behaviors when MMM is not
used.

> It's a change that can have visible effects, of course, but these are
> fairly rare and I'm hard pressed to come up with scenarios where the
> effect is anything but beneficial.

Use being so deep into the pretest requires to be either 110% careful
not to change existing behaviors, or agree to postpone this to Emacs 27.