>> You haven't shown any evidence of inefficiency.
> I think I have, in our previous discussion. I think it's clear that
> f-l-multiline properties are erased throughout the change-region, and
> have to be recalculated througout the change region, at every change.
> For most C-like languages, this will be expensive for large regions. Of
> all the CC languages, you can only determine f-l region boundaries
> cheaply in AWK (and maybe IDL). By contrast, f-l-extend-region only
> needs to do the calculation at the two ends of the changed region, and
> has to do it just as often.
I think you're comparing apples and oranges.
And even if it weren't, it's still no evidence of inefficiency (by
"evidence" I mean actual user-visible slowdown). In all the examples I've
shown, there is no calculation to be done for f-l-multiline: just add the
property at the time when you know where to put it (i.e. you've already
done the calculation for the purpose of highlighting anyway).
> This extra calculution will delay the display of fresh buffer areas when
> scrolling, for example.
I must be missing your reference again.
>> > Is there any chance of you adapting the font-lock-multiline mechanism
>> > so that the properties can be applied _before_ fontification, exactly
>> > where they are needed, rather than _after_ fontification throughout
>> > the entire change region?
>> That's the thing on the backburner. But it's still unrelated to the
>> OP's problem which was specifically about *re*fontification, where the
>> current font-lock-multiline support is all you need (and if you don't
>> like it, there are already several existing alternatives, see the
>> lispref manual).
> Could you be more explicit here, please, on what these alternatives are?
- jit-lock-defer-multiline
- your new font-lock after-change-function hook (currently called
font-lock-extend-region-function)
> I've not been aware of them up to now.
Sorry to disappoint you, you knew them.
>> > public Bar // Bar fontified as a type, at first
>> > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>> Oh, I see. It seems very minor. Why do you care? Is the performance
>> difference ever noticeable? If yes, how often?
> I don't think we should be so casual about other people's processor
> cycles. The performance difference will be very noticeable if Emacs ever
> comes to be run on application servers rather than individual desktops,
> for example. If "public Bar" were a 20-line declaration, the delay might
> well be noticeable, especially on the sort of older PC's which still
> permeate the developed world. ;-)
But the delay will be noticable anyway when editing the 20 line declaration
itself (which sems just as likely as editing a comment that follows it):
solving it for the comment is not enough, you need to be able to rehighlight
just the line that was touched, even if it was part of a long
multiline element. At this point, unless you have very long lines, having
to round up to a whole number of lines is not much of a problem either.
Anyway, I'm not opposed to your proposed change to allow
non-wholeline fontification. I doubt it'll be useful, but I can't see it
hurting either.
> Indeed, not. But doing our stuff in a way that obfuscated C works right
> at no extra cost is not a bad way to go.
Agreed, but it's very different from what font-lock was designed to do.
Stefan
_______________________________________________
emacs-pretest-bug mailing list
emacs-pretest-bug@gnu.org
http://lists.gnu.org/mailman/listinfo/emacs-pretest-bug
