Re: Mysterious fontification/C++ context issue

[David Kastrup]

Alan Mackenzie <address@hidden> writes:

> Guten Tag, David!
>
> On Sun, Dec 10, 2006 at 01:46:40PM +0100, David Kastrup wrote:
>> Alan Mackenzie <address@hidden> writes:
>
>> > With Martin Rudalics's optimisation to c-beginning-of-defun-raw, I
>> > don't feel that the slowness is too bad any more (though he does
>> > ;-).  In the extreme case xdisp.c, scrolling to EOB and M-v is
>> > mildly sluggish (about half a second), on my 5 year old Athlon 1.2
>> > GHz machine.  A typical new PC now is, say, 3 GHZ.  In the time
>> > Emacs 22 is the current release, a typical new PC will come to be
>> > around 20 GHz, and this slowness will not matter.
>
>> Please, arguments like that are just not acceptable.  If examples with
>> barely tolerable behavior can be come across easily, you can bet that
>> there will be normal use cases where the the behavior will be quite
>> intolerable.  And even on faster machines, editing should try avoiding
>> draining unnecessary CPU power: editing is by far the most important
>> application where you want to have a long battery life for laptops.
>
>> I am working with a 600MHz laptop, and my occasionally used desktop
>> system has a 233MHz processor.  The preview-latex
>> <URL:http://www.gnu.org/software/auctex/preview-latex.html> package
>> has been streamlined to operate well on such machines.  It would be
>> really a bad hoax if syntax highlighting (which does a lot less) would
>> make such machines unusable for editing with an up-to-date Emacs with
>> default settings.
>
> Hey, just calm down a bit and take a few long deep breaths!  You've
> snipped my argument and left only the supporting discussion.  I'm NOT
> arguing that anybody should have this "barely tolerable behaviour"
> thrust upon him; the user should be able to set his system up as he
> wishes.

Disagree.  The _default_ should be such that the behavior is
tolerable, without the user having to set up anything.

> I'm merely saying that in a few years time the point will be moot.

Disagree.  Non-local O(n^2) (or worse) behavior will exhaust any
advance of computing power eventually.  You've snipped my argument.

> And that for Emacs 23, we will be able to set the default value of
> open-paren-...-start to nil, just as in Emacs 22 font-locking is
> enabled by default.

We only enabled font-locking after hunting down the cases where it
lead to intolerable behavior.  Since the original behavior was not
deemed acceptable, I don't see why we should now act cavalier about
regressions.

> Hopefully Emacs will always be such that wierdos who, for whatever
> reason, want to run with font-lock disabled, or on bare TTYs, or on
> early 1990s machines can do so comfortably.  ;-)

Hopefully Emacs will work tolerably for all use cases without having
to strip it down to "weirdo level" from its default settings.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum