GNU bug report logs - #13361
24.2.91; [regression] window point incompatible change

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 14:13:28 +0800

I have just spent this morning trying to fix a 3rd party library
behaviour change only to find this annoying regression.

To reproduce

0. emacs -q
1. Create two buffers A and B and make them both visible in the frame
2. Insert some text in A and leave point at the end of buffer A
3. Switch to buffer B and eval
    
      (with-current-buffer "A" (goto-char (point-min)))

You will see point in buffer A doesn't change.

Leo

Message #8 received at 13361 <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: 13361 <at> debbugs.gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 14:32:34 +0800

Sorry not a regression. Sorry for the noise.

It is the same (albeit odd) behaviour in 24.2 too. Any idea why it
behaves so subtly like this?

Thanks,
Leo

Message #11 received at 13361 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 13361 <at> debbugs.gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 03:36:47 -0500

Leo Liu wrote:

> It is the same (albeit odd) behaviour in 24.2 too. Any idea why it
> behaves so subtly like this?

Are you asking why window-point exists and is not always equal to point?

(with-current-buffer "A"
  (message "%s:%s:%s:%s"
           (point)
           (window-point (get-buffer-window "A"))
           (progn
             (goto-char (point-min))
             (point))
           (window-point (get-buffer-window "A")))
  (sit-for 1)
  (set-window-point (get-buffer-window "A") (point-min)))

Message #16 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 17:41:16 +0800

On 2013-01-05 16:36 +0800, Glenn Morris wrote:
> Are you asking why window-point exists and is not always equal to point?

Yeah. For example some packages use with-current-buffer and move point
using goto-char and don't realise it can not be moved if the window is
visible but not current.

Leo

Message #19 received at 13361 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 13361 <at> debbugs.gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 12:27:09 +0100

> Yeah. For example some packages use with-current-buffer and move point
> using goto-char and don't realise it can not be moved if the window is
> visible but not current.

If these packages are part of Emacs, please write an appropriate bug
report.  Otherwise, kindly notify the respective author.

Thanks, martin

Message #22 received at 13361 <at> debbugs.gnu.org (full text, mbox):

From: Glenn Morris <rgm <at> gnu.org>
To: Leo Liu <sdl.web <at> gmail.com>
Cc: 13361 <at> debbugs.gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Sat, 05 Jan 2013 14:13:07 -0500

Leo Liu wrote:

> On 2013-01-05 16:36 +0800, Glenn Morris wrote:
>> Are you asking why window-point exists and is not always equal to point?
>
> Yeah. For example some packages use with-current-buffer and move point
> using goto-char and don't realise it can not be moved if the window is
> visible but not current.

As the example I gave showed, point does move. In any case, I don't see
any bug here.

Message #27 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Liu <sdl.web <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Re: bug#13361: 24.2.91; [regression] window point incompatible change
Date: Mon, 07 Jan 2013 10:31:58 +0800

On 2013-01-06 03:13 +0800, Glenn Morris wrote:
> As the example I gave showed, point does move. In any case, I don't see
> any bug here.

Point is moved in that context but it is reset to window point
immediately after the window being selected. I think this subtle point
would trip a lot of elisp authors. I have already seen one in
slime-fuzzy.el (3rd party lib).

Leo

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