GNU bug report logs - #1185
23.0.60; Doc string of region-active-p considered unhelpful

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Message #5 received at submit <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: emacs-pretest-bug <at> gnu.org
Subject: 23.0.60; Doc string of region-active-p considered unhelpful
Date: Thu, 16 Oct 2008 21:42:28 +0200

Please write in English if possible, because the Emacs maintainers
usually do not have translators to read other languages for them.

Your bug report will be posted to the emacs-pretest-bug <at> gnu.org mailing list.

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

"C-h f region-active-p RET" produces the following documentation:

  Return t if Transient Mark mode is enabled and the mark is active.
  This is NOT the best function to use to test whether a command should
  operate on the region instead of the usual behavior -- for that,
  use `use-region-p'.

This is not really helpful: it does not tell why would a Lisp program
want to use this function.  Are there any circumstances where this
function is useful, or do we keep it for compatibility reasons?

If Emacs crashed, and you have the Emacs process in the gdb debugger,
please include the output from the following gdb commands:
    `bt full' and `xbacktrace'.
If you would like to further debug the crash, please read the file
d:/gnu/emacs/etc/DEBUG for instructions.


In GNU Emacs 23.0.60.1 (i386-mingw-nt5.1.2600)
 of 2008-10-16 on HOME-C4E4A596F7
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: ENU
  value of $XMODIFIERS: nil
  locale-coding-system: cp1255
  default-enable-multibyte-characters: t

Major mode: Emacs-Lisp

Minor modes in effect:
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  global-auto-composition-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<help-echo> C-h f r <backspace> u e <backspace> s e 
- r e g <tab> <return> C-x o <down> <left> <left> <left> 
<left> <left> <left> <left> <return> <next> <up> <next> 
<prior> <prior> <prior> <prior> <next> <next> <next> 
<down> <down> <down> <C-right> <right> C-s C-w C-w 
C-w C-s C-s C-r C-r C-r <up> <help-echo> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<help-echo> <help-echo> C-x C-f a l l <tab> <return> 
C-s u s e - r e g <help-echo> <help-echo> <help-echo> 
C-x C-f <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> - 2 2 <tab> - <tab> e m <tab> 
/ l i s <tab> / a l l <tab> <return> C-s m a r k - 
a <up> C-x b s i m p <tab> <return> <next> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <help-echo> 
<help-echo> M-x r e p o r t - e <tab> <return>

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Message #10 received at 1185-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: Chong Yidong <cyd <at> stupidchicken.com>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 1185-done <at> debbugs.gnu.org
Subject: 23.0.60; Doc string of region-active-p considered unhelpful
Date: Tue, 21 Oct 2008 13:04:40 -0400

> "C-h f region-active-p RET" produces the following documentation:
>
>   Return t if Transient Mark mode is enabled and the mark is active.
>   This is NOT the best function to use to test whether a command should
>   operate on the region instead of the usual behavior -- for that,
>   use `use-region-p'.
>
> This is not really helpful: it does not tell why would a Lisp program
> want to use this function.  Are there any circumstances where this
> function is useful, or do we keep it for compatibility reasons?

The reason to use use-region-p is because that checks whether the region
is empty and compares that with use-empty-active-region.  That's what we
want for most commands that have the behavior "do X on the region if
it's active".  But in some circumstances, we don't care about whether or
not the region is empty; e.g., some commands want to deactivate the mark
if region-active-p is non-nil.

I checked in a doc fix.

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