From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Juanma Barranquero <lekktu@gmail.com>
Cc: 8711@debbugs.gnu.org, Helmut Eller <eller.helmut@gmail.com>
Subject: bug#8711: 24.0.50; binding _ to unused values with lexical-binding
Date: Thu, 02 Jun 2011 09:45:09 -0300 [thread overview]
Message-ID: <jwv1uzcjtlz.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <BANLkTi=nao0cCsha9YZjKNdNZ6kyGdUEqg@mail.gmail.com> (Juanma Barranquero's message of "Thu, 2 Jun 2011 13:17:56 +0200")
> Apparently, the macroexpansion of `dolist' invokes RESULT as
> (setq VAR nil)
> RESULT
> or, in the cl-macs `dolist', as
> (let ((VAR nil))
> RESULT)
> which I suppose has been doing for decades, but is still a bit
> strange.
That's how dolist/dotimes are defined in Common-Lisp, hence that's
how it works in cl-macs. The subr versions also do it because when we
introduced them, some people brought up the issue and it seemed there
was no point in being incompatible.
> The docstring for `dolist' does not say that VAR is set to
> nil before computing RESULT.
Indeed.
> If computing RESULT needed the last VAR, the current code precludes it
> (unless it requires VAR to be nil, of course ;-)
Yes, I do find it very odd as well, but CLHS says clearly "At the time
result-form is processed, var is bound to nil".
> And, if computing RESULT requieres an outside VAR, the programmer is
> going to be forced to use this anyway:
> (let ((VAR 'myval))
> (dolist (VAR mylist)
> ...)
> (compute-my-result VAR)) ;; with the let-bound VAR, not the dolist-bound one
Or she can just use different names rather than reusing the same
variable name.
> so setting it to nil in the (dolist (VAR LIST RESULT) ...) case does
> not bring any clear benefit, even in the non-lexical case.
Agreed.
Stefan
next prev parent reply other threads:[~2011-06-02 12:45 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-21 18:44 bug#8711: 24.0.50; binding _ to unused values with lexical-binding Helmut Eller
2011-05-23 9:01 ` Lawrence Mitchell
2011-05-23 14:24 ` Stefan Monnier
2011-05-23 18:23 ` Helmut Eller
2011-05-23 19:29 ` Stefan Monnier
2011-05-23 20:16 ` Helmut Eller
2011-05-24 0:56 ` Stefan Monnier
2011-05-24 6:01 ` Helmut Eller
2011-05-24 12:42 ` Stefan Monnier
2011-06-02 11:17 ` Juanma Barranquero
2011-06-02 12:45 ` Stefan Monnier [this message]
2011-06-02 13:41 ` Juanma Barranquero
2011-06-02 14:00 ` Stefan Monnier
2011-06-02 17:10 ` Juanma Barranquero
2011-05-23 20:32 ` Helmut Eller
2011-05-24 0:51 ` Stefan Monnier
2022-05-08 12:33 ` bug#8711: bug#26960: 26.0.50; Complaints about unused variable in cl-destructuring-bind Lars Ingebrigtsen
2022-05-08 13:32 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-05-09 9:25 ` bug#8711: " Lars Ingebrigtsen
2022-05-09 12:26 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwv1uzcjtlz.fsf-monnier+emacs@gnu.org \
--to=monnier@iro.umontreal.ca \
--cc=8711@debbugs.gnu.org \
--cc=eller.helmut@gmail.com \
--cc=lekktu@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.