Re: newline-and-indent vs. electric-indent-mode

[Dmitry Gutov]

On 25.01.2021 17:15, Stefan Monnier wrote:
> > > The problem with `whitespace-cleanup-mode` is that it's global.
> > > I'd like something that only operates locally, i.e. only touches lines
> > > you've modified.
> > That would be https://github.com/lewang/ws-butler.
>
> That's better, indeed, tho if you look at the implementation you see
> that it has to deal with lots of corner cases, so it ends up "ugly and
> brittle": I'm not sure "cleanup on save" is the better option.
> I don't mean to say that Le Wang did a bad job, BTW: the issues aren't
> caused by a bad design or implementation, but by a hard problem.

Indeed, there are a lot of hooks involved, but it seemed to work last 
time I tried it.

> I was thinking instead of something that removes the trailing space(s)
> when point leaves the line (like Madhu suggested).  Of course that's
> also fraught with danger (e.g. you don't want that whitespace to
> disappear just because you did `C-x C-x`), so the result might end up
> just as ugly&brittle.

Or if I just did C-n C-p, or something more complex to the same effect. 
But I suppose somebody could try creating a prototype, and then we'd see 
just how jarring this approach is (or not).

Alternatively, one could start with looking into how others editors do it.

> > whitespace-cleanup-mode is working out just fine for me, though, because by
> > default is only cleans files that were clean previously.
>
> I'd like a feature that is also active in non-clean files.

I just clean such a file manually once, and then the feature is active. 
Or I don't, and use whitespace-mode to make sure I don't leave new 
trailing whitespace around.

Files like that are a minority in my experience, so it's not too big a 
price to pay for being able to rely on a simple implementation. YMMV, of 
course.