* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
@ 2019-10-21 18:38 Stefan Kangas
2019-10-21 19:30 ` Eli Zaretskii
0 siblings, 1 reply; 7+ messages in thread
From: Stefan Kangas @ 2019-10-21 18:38 UTC (permalink / raw
To: 37856
I get an error when advising 'next-error' with 'recenter'.
Steps to reproduce:
1. Under "emacs -Q", evaluate:
(defun my-advice (&rest args)
(recenter))
(advice-add 'next-error :after #'my-advice)
2. M-x rgrep RET [... grep for something]
3. Run 'next-error' (M-g M-n) from the "*grep*" buffer.
Result: I get the error:
recenter-top-bottom: ‘recenter’ing a window that does not display
current-buffer.
(I also get the error when I run it in the second window when
'next-error' would take you to a different file.)
Expected result: I get no error.
---
Backtrace:
Debugger entered--Lisp error: (error "‘recenter’ing a window that does
not display curre...")
recenter()
my-advice(nil)
apply(my-advice nil)
next-error(nil)
funcall-interactively(next-error nil)
#<subr call-interactively>(next-error nil nil)
apply(#<subr call-interactively> next-error (nil nil))
call-interactively@ido-cr+-record-current-command(#<subr
call-interactively> next-error nil nil)
apply(call-interactively@ido-cr+-record-current-command #<subr
call-interactively> (next-error nil nil))
call-interactively(next-error nil nil)
command-execute(next-error)
---
This seems to be due to this code in window.c:
/* For reasons why we signal an error here, see
https://lists.gnu.org/r/emacs-devel/2014-06/msg00053.html,
https://lists.gnu.org/r/emacs-devel/2014-06/msg00094.html. */
if (buf != current_buffer)
error ("`recenter'ing a window that does not display current-buffer.");
This code was added here:
3da983f8c4 2014-06-06 Stefan Monnier * src/window.c (Frecenter):
Signal an error if window-buffer is not current-buffer.
---
In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin17.7.0, NS
appkit-1561.61 Version 10.13.6 (Build 17G8037))
of 2019-10-21 built on Stefans-MBP
Repository revision: 0e6f4628d8fff53505e4399e71da9f531a64fff7
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1561
System Description: Mac OS X 10.13.6
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 18:38 bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer Stefan Kangas
@ 2019-10-21 19:30 ` Eli Zaretskii
2019-10-21 20:11 ` Stefan Kangas
0 siblings, 1 reply; 7+ messages in thread
From: Eli Zaretskii @ 2019-10-21 19:30 UTC (permalink / raw
To: Stefan Kangas; +Cc: 37856
> From: Stefan Kangas <stefan@marxist.se>
> Date: Mon, 21 Oct 2019 20:38:47 +0200
>
> 1. Under "emacs -Q", evaluate:
> (defun my-advice (&rest args)
> (recenter))
> (advice-add 'next-error :after #'my-advice)
> 2. M-x rgrep RET [... grep for something]
> 3. Run 'next-error' (M-g M-n) from the "*grep*" buffer.
>
> Result: I get the error:
> recenter-top-bottom: ‘recenter’ing a window that does not display
> current-buffer.
Why isn't this a cockpit error: you force a function that happens to
switch buffers to recenter. It's like you've added a call to
'recenter' in some arbitrary place in a random function: you are
responsible for that code, and if it does stuff that it shouldn't,
your code is wrong. No?
> This seems to be due to this code in window.c:
>
> /* For reasons why we signal an error here, see
> https://lists.gnu.org/r/emacs-devel/2014-06/msg00053.html,
> https://lists.gnu.org/r/emacs-devel/2014-06/msg00094.html. */
> if (buf != current_buffer)
> error ("`recenter'ing a window that does not display current-buffer.");
Yes, and that's on purpose, see the cited discussion.
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 19:30 ` Eli Zaretskii
@ 2019-10-21 20:11 ` Stefan Kangas
2019-10-21 21:37 ` Juanma Barranquero
2019-10-22 2:28 ` Eli Zaretskii
0 siblings, 2 replies; 7+ messages in thread
From: Stefan Kangas @ 2019-10-21 20:11 UTC (permalink / raw
To: Eli Zaretskii; +Cc: 37856
Eli Zaretskii <eliz@gnu.org> writes:
> > 1. Under "emacs -Q", evaluate:
> > (defun my-advice (&rest args)
> > (recenter))
> > (advice-add 'next-error :after #'my-advice)
> > 2. M-x rgrep RET [... grep for something]
> > 3. Run 'next-error' (M-g M-n) from the "*grep*" buffer.
> >
> > Result: I get the error:
> > recenter-top-bottom: ‘recenter’ing a window that does not display
> > current-buffer.
>
> Why isn't this a cockpit error: you force a function that happens to
> switch buffers to recenter. It's like you've added a call to
> 'recenter' in some arbitrary place in a random function: you are
> responsible for that code, and if it does stuff that it shouldn't,
> your code is wrong. No?
In this case my expectation was that this code would be run *after*
the command, i.e. when it had already done all the switching. I'm not
sure that's comparable to placing recenter in an arbitrary place
inside the function.
It was surprising to me that this didn't work, and it's not clear what
I should do instead. For example, the following code exhibits the
same problem:
(defun my-next-error ()
(interactive)
(next-error)
(recenter))
What am I missing?
Best regards,
Stefan Kangas
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 20:11 ` Stefan Kangas
@ 2019-10-21 21:37 ` Juanma Barranquero
2019-10-21 22:19 ` Stefan Kangas
2019-10-22 2:28 ` Eli Zaretskii
1 sibling, 1 reply; 7+ messages in thread
From: Juanma Barranquero @ 2019-10-21 21:37 UTC (permalink / raw
To: Stefan Kangas; +Cc: 37856
[-- Attachment #1: Type: text/plain, Size: 238 bytes --]
On Mon, Oct 21, 2019 at 10:13 PM Stefan Kangas <stefan@marxist.se> wrote:
> (defun my-next-error ()
> (interactive)
> (next-error)
> (recenter))
>
> What am I missing?
What's wrong with
(add-hook 'next-error-hook 'recenter)
?
[-- Attachment #2: Type: text/html, Size: 444 bytes --]
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 21:37 ` Juanma Barranquero
@ 2019-10-21 22:19 ` Stefan Kangas
2019-10-22 7:56 ` Robert Pluim
0 siblings, 1 reply; 7+ messages in thread
From: Stefan Kangas @ 2019-10-21 22:19 UTC (permalink / raw
To: Juanma Barranquero; +Cc: 37856-done
Juanma Barranquero <lekktu@gmail.com> writes:
> > What am I missing?
>
> What's wrong with
>
> (add-hook 'next-error-hook 'recenter)
Oops, how silly of me. Yes, I'll just use that. Thanks.
I'm still a bit confounded by the above behaviour, but if everyone
else feels that everything is in order I'll just go ahead and close
this. Sorry about the noise.
Best regards,
Stefan Kangas
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 20:11 ` Stefan Kangas
2019-10-21 21:37 ` Juanma Barranquero
@ 2019-10-22 2:28 ` Eli Zaretskii
1 sibling, 0 replies; 7+ messages in thread
From: Eli Zaretskii @ 2019-10-22 2:28 UTC (permalink / raw
To: Stefan Kangas; +Cc: 37856
> From: Stefan Kangas <stefan@marxist.se>
> Date: Mon, 21 Oct 2019 22:11:50 +0200
> Cc: 37856@debbugs.gnu.org
>
> It was surprising to me that this didn't work, and it's not clear what
> I should do instead. For example, the following code exhibits the
> same problem:
>
> (defun my-next-error ()
> (interactive)
> (next-error)
> (recenter))
>
> What am I missing?
The advice effectively "injects" your code into the advised function,
just before it returns.
^ permalink raw reply [flat|nested] 7+ messages in thread
* bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer
2019-10-21 22:19 ` Stefan Kangas
@ 2019-10-22 7:56 ` Robert Pluim
0 siblings, 0 replies; 7+ messages in thread
From: Robert Pluim @ 2019-10-22 7:56 UTC (permalink / raw
To: 37856; +Cc: stefan
>>>>> On Tue, 22 Oct 2019 00:19:13 +0200, Stefan Kangas <stefan@marxist.se> said:
Stefan> Juanma Barranquero <lekktu@gmail.com> writes:
>> > What am I missing?
>>
>> What's wrong with
>>
>> (add-hook 'next-error-hook 'recenter)
Stefan> Oops, how silly of me. Yes, I'll just use that. Thanks.
Stefan> I'm still a bit confounded by the above behaviour, but if everyone
Stefan> else feels that everything is in order I'll just go ahead and close
Stefan> this. Sorry about the noise.
The add-function docstring says:
Add a piece of advice on the function stored at PLACE.
FUNCTION describes the code to add. WHERE describes where to add it.
WHERE can be explained by showing the resulting new function, as the
result of combining FUNCTION and the previous value of PLACE, which we
call OLDFUN here:
`:before' (lambda (&rest r) (apply FUNCTION r) (apply OLDFUN r))
`:after' (lambda (&rest r) (prog1 (apply OLDFUN r) (apply FUNCTION r)))
`:around' (lambda (&rest r) (apply FUNCTION OLDFUN r))
so I think Iʼd agree with your expectations. Of course, you could use
:around and call 'next-error' yourself in your function (untested).
Robert
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2019-10-22 7:56 UTC | newest]
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2019-10-21 18:38 bug#37856: 27.0.50; 'next-error' advised with 'recenter' signals error when run from "*grep*" buffer Stefan Kangas
2019-10-21 19:30 ` Eli Zaretskii
2019-10-21 20:11 ` Stefan Kangas
2019-10-21 21:37 ` Juanma Barranquero
2019-10-21 22:19 ` Stefan Kangas
2019-10-22 7:56 ` Robert Pluim
2019-10-22 2:28 ` Eli Zaretskii
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