GNU bug report logs - #79246
31.0.50; cond* bind* variable scope - documentation

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

From: Lester Longley <lester <at> ieee.org>
To: bug-gnu-emacs <at> gnu.org
Subject: 31.0.50; cond* bind* variable scope - documentation
Date: Fri, 15 Aug 2025 14:14:02 -0400

[Message part 1 (text/plain, inline)]

Please see the following excerpt from lisp/emacs-lisp/cond-star.el:

     `(bind* BINDINGS...)' means to bind BINDINGS (as if they were in
`let*')
     for the body of the clause, and all subsequent clauses, since the
`bind*'
     clause is always a non-exit clause.  As a condition, it counts as true
     and runs the body of the clause if the first binding's value is
non-nil.

However, the above qualifier "and all subsequent clauses" is missing from
(info "(elisp) cond* Macro") / doc/lispref/control.texi:

     ‘(bind* BINDINGS...)’ means to bind BINDINGS (like the bindings
     list in ‘let*’, *note Local Variables::) for the body of the
     clause.  As a condition, it counts as true if the first binding’s
     value is non-‘nil’.

I believe that it would be helpful for doc/lispref/control.texi to be
updated with that additional information (i.e., from
lisp/emacs-lisp/cond-star.el), since it's useful in understanding how & why
bind* works.

This aspect was explained in
https://lists.gnu.org/archive/html/emacs-devel/2025-01/msg00429.html:

> That is the purpose of bind*: to bind variables that reach over
subsequent clauses.

... which is where I first noticed it, since (I think) it's not in the
manual.

Thanks,
Lester

In GNU Emacs 31.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.38, cairo version 1.16.0) of 2025-08-11 built on penguin
Repository revision: 66eead6fd06d40b919ee6d1de86099592729d671
Repository branch: master
System Description: Debian GNU/Linux 12 (bookworm)

Configured using:
 'configure --with-pgtk 'CFLAGS=-g -O2
 -ffile-prefix-map=/tmp/emacs.git=. -fstack-protector-strong -Wformat
 -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
 -D_FORTIFY_SOURCE=2' LDFLAGS=-Wl,-z,relro'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NATIVE_COMP NOTIFY
INOTIFY PDUMPER PGTK PNG RSVG SECCOMP SOUND THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP XIM GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
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  show-paren-mode: t
  electric-indent-mode: t
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  menu-bar-mode: t
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  font-lock-mode: t
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  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
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  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
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bytecomp byte-compile comp-common rx emacsbug lisp-mnt message mailcap
yank-media puny dired dired-loaddefs rfc822 mml mml-sec password-cache
epa derived epg rfc6068 epg-config gnus-util text-property-search
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threads dbusbind inotify dynamic-setting system-font-setting
font-render-setting cairo gtk pgtk lcms2 multi-tty move-toolbar
make-network-process tty-child-frames native-compile emacs)

Memory information:
((conses 16 66922 14238) (symbols 48 6803 0) (strings 32 17289 2551)
 (string-bytes 1 550776) (vectors 16 11399)
 (vector-slots 8 154109 11674) (floats 8 22 13) (intervals 56 252 0)
 (buffers 1064 11))

[Message part 2 (text/html, inline)]

Message #8 received at 79246 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Lester Longley <lester <at> ieee.org>, Richard Stallman <rms <at> gnu.org>
Cc: 79246 <at> debbugs.gnu.org
Subject: Re: bug#79246: 31.0.50; cond* bind* variable scope - documentation
Date: Sat, 16 Aug 2025 12:49:17 +0300

> Date: Fri, 15 Aug 2025 14:14:02 -0400
> From:  Lester Longley via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> 
> Please see the following excerpt from lisp/emacs-lisp/cond-star.el:
> 
>      `(bind* BINDINGS...)' means to bind BINDINGS (as if they were in `let*')
>      for the body of the clause, and all subsequent clauses, since the `bind*'
>      clause is always a non-exit clause.  As a condition, it counts as true
>      and runs the body of the clause if the first binding's value is non-nil.
> 
> However, the above qualifier "and all subsequent clauses" is missing from (info "(elisp) cond* Macro") /
> doc/lispref/control.texi:
> 
>      ‘(bind* BINDINGS...)’ means to bind BINDINGS (like the bindings
>      list in ‘let*’, *note Local Variables::) for the body of the
>      clause.  As a condition, it counts as true if the first binding’s
>      value is non-‘nil’.
> 
> I believe that it would be helpful for doc/lispref/control.texi to be updated with that additional information (i.e.,
> from lisp/emacs-lisp/cond-star.el), since it's useful in understanding how & why bind* works.
> 
> This aspect was explained in https://lists.gnu.org/archive/html/emacs-devel/2025-01/msg00429.html:
> 
> > That is the purpose of bind*: to bind variables that reach over subsequent clauses.
> 
> ... which is where I first noticed it, since (I think) it's not in the manual.

Richard, it looks like you haven't updated the ELisp manual due to the
change mentioned in
https://lists.gnu.org/archive/html/emacs-devel/2025-01/msg00429.html,
where you wrote:

  All bind* clauses are now defined to be non-exit clauses.

AFAICT, this is not in the ELisp manual yet.

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