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

[Alan Mackenzie <acm@muc.de>]

Hello, Stefan.

On Thu, Nov 30, 2017 at 18:03:05 -0500, Stefan Monnier wrote:
> > Using narrowing for marking the bounds of a sub-mode is a bad thing,
> > since it is likely to cause contention with other uses of narrowing.

> Dmitry's solution to this threat is to say that indent-line-function
> should always be called fully-widened, .....

That is a horrible, confusing, restriction, and an incompatibility with
older and other Emacsen.

> .... so there can be no "other uses of narrowing" that can get in the
> way.

The indent-line-function will be calling low-level functions which
themselves widen, possibly to determine whether point-min is in a
literal, or more generally to determine context.  These low-level
functions will also be called from other contexts, hence the necessity
of widening.

> > It's not clear what is meant here, but mandating maintainers of major
> > modes to use narrowing in a particular way is at best controversial, and
> > probably will render many major modes non-functional.

> It doesn't mandate that major modes use narrowing.  Quite the opposite:
> it says "don't touch narrowing inside your indentation function (unless
> you know what you're doing), because it's already setup for you".

That is mandating the way major modes use (or don't use) narrowing.
It's entirely the wrong thing to do, and will lead to trouble.  Whatever
this abuse of narrowing is trying to achieve can be done in other less
damaging ways.

>         Stefan

-- 
Alan Mackenzie (Nuremberg, Germany).