GNU bug report logs - #16816
24.3.50; erroneous docstring in with-temp-buffer-window

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

From: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>
To: bug-gnu-emacs <at> gnu.org
Subject: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Wed, 19 Feb 2014 22:29:27 +0100

The docstring of `with-temp-buffer-window' contains :

   It does not make the buffer current for BODY.

(2nd sentence of 2nd paragraph).

But I think that is wrong, because :
(with-temp-buffer-window
        (get-buffer-create "foo")
        nil
        nil
        (message "curbuf: %s"
                 (current-buffer)))

outputs "curbuf: foo"

If this is a docbug, here's a suggestion :

--- a/lisp/window.el
+++ b/lisp/window.el
@@ -149,10 +149,9 @@ BUFFER-OR-NAME must specify either a live buffer, or the name of a
 buffer (if it does not exist, this macro creates it).
 
 This construct makes buffer BUFFER-OR-NAME empty before running BODY.
-It does not make the buffer current for BODY.
-Instead it binds `standard-output' to that buffer, so that output
-generated with `prin1' and similar functions in BODY goes into
-the buffer.
+It makes the buffer current for BODY and binds `standard-output' to that
+buffer, so that output generated with `prin1' and similar functions in
+BODY goes into the buffer.
 
 At the end of BODY, this marks the specified buffer unmodified and
 read-only, and displays it in a window (but does not select it, or make



-- 
Nico.

Message #8 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>
Cc: 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Fri, 21 Feb 2014 14:08:43 +0100

> The docstring of `with-temp-buffer-window' contains :
>
>    It does not make the buffer current for BODY.
>
> (2nd sentence of 2nd paragraph).
>
> But I think that is wrong, because :
> (with-temp-buffer-window
>         (get-buffer-create "foo")
>         nil
>         nil
>         (message "curbuf: %s"
>                  (current-buffer)))
>
> outputs "curbuf: foo"
>
> If this is a docbug, here's a suggestion :
>
> --- a/lisp/window.el
> +++ b/lisp/window.el
> @@ -149,10 +149,9 @@ BUFFER-OR-NAME must specify either a live buffer, or the name of a
>  buffer (if it does not exist, this macro creates it).
>
>  This construct makes buffer BUFFER-OR-NAME empty before running BODY.
> -It does not make the buffer current for BODY.
> -Instead it binds `standard-output' to that buffer, so that output
> -generated with `prin1' and similar functions in BODY goes into
> -the buffer.
> +It makes the buffer current for BODY and binds `standard-output' to that
> +buffer, so that output generated with `prin1' and similar functions in
> +BODY goes into the buffer.
>
>  At the end of BODY, this marks the specified buffer unmodified and
>  read-only, and displays it in a window (but does not select it, or make

`with-temp-buffer-window' should behave as `with-output-to-temp-buffer'
in this regard (at least I hope so).  So in revision 116509 I moved the
evaluation of BODY out of the scope of `with-current-buffer'.  If this
causes problems, I will revert and use your patch.

Thanks, martin

Message #15 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 16:32:09 +0100

reopen 16816
quit

On Fri, Feb 21, 2014 at 2:08 PM, martin rudalics <rudalics <at> gmx.at> wrote:

> `with-temp-buffer-window' should behave as `with-output-to-temp-buffer'
> in this regard (at least I hope so).  So in revision 116509 I moved the
> evaluation of BODY out of the scope of `with-current-buffer'.  If this
> causes problems, I will revert and use your patch.

This breaks with-help-window. Try

 emacs -Q
 C-x C-h

the help output is inserted in the current buffer (*scratch*, in this case).

This patch fixes it.

=== modified file 'lisp/help.el'
--- lisp/help.el 2014-02-10 01:34:22 +0000
+++ lisp/help.el 2014-02-27 15:29:05 +0000
@@ -1207,7 +1207,8 @@
    (temp-buffer-window-show-hook
     (cons 'help-mode-finish temp-buffer-window-show-hook)))
        (with-temp-buffer-window
- ,buffer-name nil 'help-window-setup (progn ,@body)))))
+ ,buffer-name nil 'help-window-setup
+ (with-current-buffer ,buffer-name ,@body)))))

 ;; Called from C, on encountering `help-char' when reading a char.
 ;; Don't print to *Help*; that would clobber Help history.

Message #20 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 19:44:55 +0100

> This breaks with-help-window. Try
>
>  emacs -Q
>  C-x C-h
>
> the help output is inserted in the current buffer (*scratch*, in this case).

Yes.  A lousy bug.  I introduced it last year relying on the misfeature
that `with-temp-buffer-window' makes the help buffer current.  Does the
following patch fix it?

=== modified file 'lisp/help.el'
--- lisp/help.el	2014-02-10 01:34:22 +0000
+++ lisp/help.el	2014-02-27 18:31:30 +0000
@@ -498,7 +498,8 @@
 then we display only bindings that start with that prefix."
   (let ((buf (current-buffer)))
     (with-help-window (help-buffer)
-      (describe-buffer-bindings buf prefix menus))))
+      (with-current-buffer (help-buffer)
+	(describe-buffer-bindings buf prefix menus)))))

 (defun where-is (definition &optional insert)
   "Print message listing key sequences that invoke the command DEFINITION.

> This patch fixes it.
>
> === modified file 'lisp/help.el'
> --- lisp/help.el 2014-02-10 01:34:22 +0000
> +++ lisp/help.el 2014-02-27 15:29:05 +0000
> @@ -1207,7 +1207,8 @@
>     (temp-buffer-window-show-hook
>      (cons 'help-mode-finish temp-buffer-window-show-hook)))
>         (with-temp-buffer-window
> - ,buffer-name nil 'help-window-setup (progn ,@body)))))
> + ,buffer-name nil 'help-window-setup
> + (with-current-buffer ,buffer-name ,@body)))))
>
>  ;; Called from C, on encountering `help-char' when reading a char.
>  ;; Don't print to *Help*; that would clobber Help history.
>

This would restore what we had till now: BODY would get evaluated in the
help buffer and not in the original buffer.  I doubt this could have any
serious consequences (Emacs 24.3 runs this already for quite some time)
but it's inherently disturbing.

martin

Message #23 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 19:55:35 +0100

On Thu, Feb 27, 2014 at 7:44 PM, martin rudalics <rudalics <at> gmx.at> wrote:

> Does the following patch fix it?

Yes.

> This would restore what we had till now: BODY would get evaluated in the
> help buffer and not in the original buffer.  I doubt this could have any
> serious consequences (Emacs 24.3 runs this already for quite some time)
> but it's inherently disturbing.

You're right, I suppose.

BTW, the docstring of with-help-window isn't exactly clear to me...

  Display buffer with name BUFFER-NAME in a help window evaluating BODY.

Evaluating BODY in a help window? What does this mean?

     J

Message #26 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 21:00:36 +0100

> BTW, the docstring of with-help-window isn't exactly clear to me...
>
>   Display buffer with name BUFFER-NAME in a help window evaluating BODY.
>
> Evaluating BODY in a help window? What does this mean?

Drew's getting old.  Such an awful doc-string and he apparently never
complained ...

I'll have to fix the info entry too.  It doesn't even say that the
buffer gets displayed.

martin

Message #29 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: Drew Adams <drew.adams <at> oracle.com>
To: martin rudalics <rudalics <at> gmx.at>, Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: RE: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Thu, 27 Feb 2014 13:04:21 -0800 (PST)

>  > BTW, the docstring of with-help-window isn't exactly clear to me...
>  >   Display buffer with name BUFFER-NAME in a help window evaluating BODY.
>  > Evaluating BODY in a help window? What does this mean?
> 
> Drew's getting old.

Everyone's getting old, from Day Zero on.

> Such an awful doc-string and he apparently never complained ...

So many bugs, so little time.  Fortunately, Juanma is there.

Message #32 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Fri, 28 Feb 2014 11:58:59 +0100

>> This would restore what we had till now: BODY would get evaluated in the
>> help buffer and not in the original buffer.  I doubt this could have any
>> serious consequences (Emacs 24.3 runs this already for quite some time)
>> but it's inherently disturbing.
>
> You're right, I suppose.

I reverted my previous change.  It's too dangerous as the bug you
reported demonstrates.

> BTW, the docstring of with-help-window isn't exactly clear to me...
>
>   Display buffer with name BUFFER-NAME in a help window evaluating BODY.
>
> Evaluating BODY in a help window? What does this mean?

I rewrote the doc-strings of `with-temp-buffer-window' and
`with-help-window'.  Please have a look.

martin

Message #35 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>
Cc: 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Fri, 28 Feb 2014 11:59:11 +0100

> If this is a docbug, here's a suggestion :

I made it a docbug now and largely expanded the doc-string based on your
suggestion.

martin

Message #38 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Juanma Barranquero <lekktu <at> gmail.com>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Sun, 16 Mar 2014 11:00:38 +0100

> This breaks with-help-window. Try
>
>  emacs -Q
>  C-x C-h
>
> the help output is inserted in the current buffer (*scratch*, in this case).

Should be now fixed in the way I proposed initially.  Please check.

Thanks, martin

Message #41 received at 16816 <at> debbugs.gnu.org (full text, mbox):

From: Juanma Barranquero <lekktu <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: Nicolas Richard <theonewiththeevillook <at> yahoo.fr>, 16816 <at> debbugs.gnu.org
Subject: Re: bug#16816: 24.3.50; erroneous docstring in with-temp-buffer-window
Date: Sat, 22 Mar 2014 06:19:16 +0100

On Sun, Mar 16, 2014 at 11:00 AM, martin rudalics <rudalics <at> gmx.at> wrote:

> Should be now fixed in the way I proposed initially.  Please check.

Sorry, I forgot about this one. It works, of course.

Thanks,

   J

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