From: Michael Heerdegen <michael_heerdegen@web.de>
To: help-gnu-emacs@gnu.org
Subject: Re: Example use of macro to minimize and generalize the code
Date: Tue, 01 Jun 2021 01:37:28 +0200 [thread overview]
Message-ID: <87y2buscef.fsf@web.de> (raw)
In-Reply-To: YLVXslhB17GNcQTT@protected.localdomain
Jean Louis <bugs@gnu.support> writes:
> (defmacro when-tabulated-id (table id &rest body)
> (declare (indent 2) (debug t))
> (ignore id)
> `(if id
> (progn
> ,@body)
> (if (or (eq ,table 'any)
> (string-equal ,table rcd-current-table))
> (let ((id (tabulated-list-get-id)))
> (if id
> (progn ,@body)
> (message "Did not get ID")))
> (message "This function is for table `%s' only" ,table))))
There is something wrong with that definition however: the variable `id'
is completely ignored, specifying something at that argument position is
redundant.
Tt may "work" by accident if the symbol `id' happens to be dynamically
bound to the same thing that you specify as argument, but only when that
exact variable name is used and only in dynamically binding Lisp.
Normally the byte compiler warns about this kind of problem - of course
only if you don't silence it ;-)
Michael.
next prev parent reply other threads:[~2021-05-31 23:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-30 22:48 Why is defun not executed during load-file? Drew Adams
2021-05-30 22:57 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 2:05 ` [External] : " Drew Adams
2021-05-31 2:56 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 5:05 ` Drew Adams
2021-05-31 19:20 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 19:47 ` Stefan Monnier via Users list for the GNU Emacs text editor
2021-05-31 20:09 ` Marcin Borkowski
2021-06-07 2:19 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-06-07 6:27 ` Jean Louis
2021-06-07 14:18 ` FW: " Drew Adams
2021-06-07 14:41 ` Emanuel Berg via Users list for the GNU Emacs text editor
2021-05-31 21:40 ` Example use of macro to minimize and generalize the code Jean Louis
2021-05-31 23:37 ` Michael Heerdegen [this message]
2021-05-31 23:59 ` Jean Louis
2021-06-01 0:34 ` Michael Heerdegen
2021-06-01 0:39 ` Jean Louis
2021-06-01 0:59 ` Michael Heerdegen
2021-06-01 1:25 ` Jean Louis
2021-06-01 14:02 ` Michael Heerdegen
2021-06-01 16:33 ` Jean Louis
2021-06-01 16:54 ` Yuri Khan
2021-06-01 17:24 ` Jean Louis
2021-06-01 17:57 ` Yuri Khan
2021-06-01 18:12 ` Jean Louis
2021-05-31 21:45 ` Example use of macro to minimize and generalize the code (2) Jean Louis
2021-05-31 21:48 ` [External] : Re: Why is defun not executed during load-file? Michael Heerdegen
2021-05-31 23:41 ` Drew Adams
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
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87y2buscef.fsf@web.de \
--to=michael_heerdegen@web.de \
--cc=help-gnu-emacs@gnu.org \
/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.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).