From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Alan Mackenzie <acm@muc.de>
Cc: Miles Bader <miles@gnu.org>, emacs-devel@gnu.org
Subject: Re: end-of-defun is fubsr.
Date: Tue, 03 Feb 2009 21:21:02 -0500 [thread overview]
Message-ID: <jwvk587rmev.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <20090204001445.GI1396@muc.de> (Alan Mackenzie's message of "Wed, 4 Feb 2009 00:14:45 +0000")
> Visit src/buffer.c, goto L313 which contains the closing brace of DEFUN
> Fget_file_buffer, put point AFTER the "}". Or put point on the next line
> (L314). In either case C-M-e leaves point at BOL315.
Oh, so we just disagree about what is the correct behavior. As far as
I'm concerned, if C-M-e gets you to BOL315, that means that the end of
the function is BOL315, which implies that EOL313 is inside the
function, so it's correct for C-M-e to just move to BOL315.
> If one were to define a variable end-of-defun-RAW-function, which is
> defined to leave point just after the last bit of the function,
That's what end-of-defun-function should do, indeed.
> perhaps that would work, but it would break existing 3rd party code.
Like which code?
>> Unless by "the problem" you're talking about the performance problem, in
>> which case I understand that each time we call BOD (except for the first
>> call), we know that we're "outside" of a defun (unless there's nesting,
>> of course) but we don't tell that to BOD which may have to redo the work
>> of figuring it out.
> WILL have to do the work.
No: in most cases, beginning-of-defun-raw just uses a simple regexp and
doesn't try to determine its position in the syntax tree before doing
its job. This is pretty much how C-mode's beginning-of-defun worked in
Emacs-21 and incidentally it worked (for the cases I care about) much
better than the current code.
> Now, I wonder, who could that have been? ;-) Oh, how I'd love just to
> get rid of these stupid K&R declarations, which NOBODY uses at all
> nowadays, except on >20 year old code bases. ;-) Why don't we flush
> them out of Emacs C source? (No, you don't have to answer.)
Feel free to remove support for those things in C-mode. If that can
solve the performance issues, I'm all for it. After all, Emacs-21
didn't get it right and I haven't heard significant complains about it.
It's not like Emacs is always expected to understand every little bit of
a language's syntax anyway.
>> > It's changed from "move to next end of function" to "move to the end of
>> > the function at whose beginning we now are",
>> Right. As you may notice, the second is a subset of the first (with
>> a few caveats for nested functions, of course, but that shouldn't matter
>> for C-mode), so if your implementation works for the first, it should
>> work for the second as well. It's called backward compatibility.
> c-end-of-defun's functionality "needs" to stay the same to support other
> Emacsen. For Emacs-23's EOD-function, It would barely need to be more
> than
> (search-forward-regexp "{")
> (backward-char)
> (foward-sexp)
Yes, simplicity of implementation of EOD-function was indeed an
important motivation in my code changes.
>> > and its default value is `forward-sexp'. `c-end-of-defun' was a good
>> > fit for the variable as it formerly was, but is now
>> > severely suboptimal.
>> At most by a factor of 2. I.e. if it's slow now, it sure wasn't
>> zippy before.
> By a factor a great deal more than 2, highly dependent on ARG.
The only case I care about for now is when ARG=1. As long as this case
is slow, there's no point complaining that end-of-defun makes it too
slow for ARG=106.
>> >> Not sure about restoring the previous semantics. But I could agree to
>> >> the additional ARG argument, which could even let it "take over" (so
>> >> beginning-of-defun-raw is not called in that case).
>> > :-) Let's do it!
>> I knew you'd like it.
> :-)
I'm still wondering whether we couldn't just turn end-of-defun into
a simple variant of
(BOD-raw N)
(funcall EOD-function)
> OK. I think I can see what you're saying, now. Were you thinking of any
> (non CC Mode) languages in particular? Did this ever get discussed on
> emacs-devel? I might well have been asleep at the time.
No, I don't remember discussing it much. It did come out of
a discussion where it became apparent that end-of-defun was broken
(especially when called with negative args).
Stefan
next prev parent reply other threads:[~2009-02-04 2:21 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-02 8:13 end-of-defun acts weirdly in c-mode; also, mark-defun in c-mode Miles Bader
2009-02-02 20:27 ` Alan Mackenzie
2009-02-02 22:46 ` Stefan Monnier
2009-02-03 9:17 ` Miles Bader
2009-02-03 10:50 ` Alan Mackenzie
2009-02-03 11:23 ` Miles Bader
2009-02-03 11:35 ` Miles Bader
2009-02-03 12:29 ` Alan Mackenzie
2009-02-03 13:00 ` Alan Mackenzie
2009-02-03 16:09 ` end-of-defun is fubsr. [Was: end-of-defun acts weirdly in c-mode] Alan Mackenzie
2009-02-03 15:56 ` Juanma Barranquero
2009-02-03 16:34 ` end-of-defun is fubsr Chong Yidong
2009-02-03 17:18 ` Andreas Roehler
2009-02-04 11:33 ` Alan Mackenzie
2009-02-04 14:54 ` Andreas Roehler
2009-02-03 16:40 ` end-of-defun is fubsr. [Was: end-of-defun acts weirdly in c-mode] Alan Mackenzie
2009-02-03 17:13 ` end-of-defun is fubsr Stefan Monnier
2009-02-03 18:58 ` Alan Mackenzie
2009-02-03 20:50 ` Stefan Monnier
2009-02-04 0:14 ` Alan Mackenzie
2009-02-04 2:21 ` Stefan Monnier [this message]
2009-02-04 13:37 ` Alan Mackenzie
2009-02-04 14:29 ` Stefan Monnier
2009-02-04 15:44 ` Alan Mackenzie
2009-02-05 10:37 ` Andreas Roehler
2009-02-12 21:35 ` Stefan Monnier
2009-02-13 11:08 ` Alan Mackenzie
2009-02-13 14:31 ` Stefan Monnier
2009-02-13 16:42 ` Alan Mackenzie
2009-02-13 17:06 ` Stefan Monnier
2009-02-13 18:57 ` Alan Mackenzie
2009-02-14 4:22 ` Stefan Monnier
2009-02-14 18:00 ` Alan Mackenzie
2009-02-14 21:16 ` Stefan Monnier
2009-02-14 23:25 ` Alan Mackenzie
2009-02-15 0:57 ` Miles Bader
2009-02-15 19:26 ` Stefan Monnier
2009-02-15 22:00 ` Alan Mackenzie
2009-02-05 11:44 ` Problems C Mode has with src/regex.c [was: end-of-defun is fubsr.] Alan Mackenzie
2009-02-05 21:50 ` end-of-defun acts weirdly in c-mode Alan Mackenzie
2009-02-06 1:03 ` Glenn Morris
2009-02-06 12:23 ` Alan Mackenzie
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