Re: CC Mode with font-lock-maximum-decoration 2

[Alan Mackenzie <acm@muc.de>]

Hello, Eli.

On Tue, Aug 09, 2022 at 19:59:36 +0300, Eli Zaretskii wrote:
> > Date: Tue, 9 Aug 2022 16:36:04 +0000
> > Cc: emacs-devel@gnu.org
> > From: Alan Mackenzie <acm@muc.de>

> > > We are not talking about my personal customizations, we are talking
> > > about what CC Mode does by default.  If we'd changed the default to be
> > > level 2 for CC Mode, I could understand your line of reasoning.  But
> > > since you don't think this should be the default, I say what CC Mode
> > > does at level 2 is not of practical importance for making CC Mode fast
> > > enough.

> > Fast enough for what?

> Fast enough for editing free of annoying delays and sluggishness.

What's annoying and sluggish for Alice is perfectly fine for Bob.
Everybody's different.

> > CC Mode at level 3 is fast enough for many, probably most, users.

> I don't think so.  How am I different from other users?

You're probably a lot faster than most users at just about everything
you do.  How else could you keep Emacs under control?  If your mental
processes are faster than most people's, then what's sluggish to you
would be perfectly OK to other people.  Everybody's different.

> If you think I always use an unoptimized build, you are wrong: my
> production sessions run fully optimized builds, and CC Mode still
> feels sluggish, perhaps because I unconsciously compare it with other
> major mode (like ELisp).

Emacs Lisp Mode cannot help but be much faster than CC Mode.  It is
unreasonable to expect parity in their speeds.

> > Over the years there've been fewer complaints about speed than
> > correctness, and most of these have been in connection with unusual
> > files.  There's never any objection to more speed, but for those who
> > really want instantaneous response, there is level 2, or even level
> > 1, and beyond that, fundamental-mode.

> What you describe is factually incorrect, but I don't want to argue
> about whether we did or didn't have complaints.  I'm complaining now
> (and did so a few months ago, but maybe you forgot).

No, I haven't forgotten.

> > I do assume that you use level 2 when you're a user (as distinct
> > from the maintainer).  Am I right?

> No, you are wrong.  I use the default all the time.  And since you
> didn't really describe the effect of going down to level 2, I cannot
> even begin thinking whether using level 2 is worth considering for my
> purposes.

Well, you could always try it out for an evening.  I think I've
described it reasonably well - faster, but less accurate.  It doesn't
seem worth the time it would take to catalogue each deficiency in its
fontification.  Maybe the inaccuracies would annoy you less than the
sluggishness of level 3.  Clearly you don't think so, but only you can
say.

But I don't like your proposed solution, which you've mentioned several
times, namely to make level 3 more like level 2.  I.e., to deliberately
reduce its accuracy in the name of speed.

-- 
Alan Mackenzie (Nuremberg, Germany).