From: Thierry Volpiatto <thierry.volpiatto@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: About a programming tip
Date: Thu, 21 Feb 2013 07:42:55 +0100 [thread overview]
Message-ID: <87y5eixj4g.fsf@gmail.com> (raw)
In-Reply-To: 20130221095112.1c8466f4687368f36805ea40@gmail.com
Xue Fuqiao <xfq.free@gmail.com> writes:
> In (info "(elisp) Programming Tips"):
>
> * In `interactive', if you use a Lisp expression to produce a list
> of arguments, don't try to provide the "correct" default values for
> region or position arguments.
> [...]
> You do not need to take such precautions when you use interactive
> specs `d', `m' and `r', because they make special arrangements to
> recompute the argument values on repetition of the command.
>
> I'm confused with these two sentences. The first sentence says that
> "don't try to provide the 'correct' default values for region or
> position arguments", but the second sentence says that "you don't need
> to take such precautions when you use interactive specs `d', `m' and
> `r'". IIRC the specs `d', `m' and `r' are "region or position
> arguments". Where do I understand wrong, or is it a bug? Thanks.
(defun foo-1 (beg end)
(interactive (list (read-number "Beg: " (region-beginning))
(read-number "End: " (region-end))))
(message "%S" (buffer-substring beg end)))
(defun foo (beg end)
(interactive "r")
(message "%S" (buffer-substring beg end)))
In other words you don't have to use foo-1, it is easier to use foo.
--
Thierry
Get my Gnupg key:
gpg --keyserver pgp.mit.edu --recv-keys 59F29997
next prev parent reply other threads:[~2013-02-21 6:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-21 1:51 About a programming tip Xue Fuqiao
2013-02-21 6:42 ` Thierry Volpiatto [this message]
2013-02-21 7:00 ` Andreas Röhler
2013-02-21 7:59 ` Thierry Volpiatto
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=87y5eixj4g.fsf@gmail.com \
--to=thierry.volpiatto@gmail.com \
--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).