From: Francis Moreau <francis.moro@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: Basic questions about elisp
Date: Thu, 5 Nov 2009 06:29:03 -0800 (PST) [thread overview]
Message-ID: <258bd70d-d192-4007-8ebe-754724d6899c@m16g2000yqc.googlegroups.com> (raw)
In-Reply-To: mailman.10122.1257425638.2239.help-gnu-emacs@gnu.org
On Nov 5, 1:57 pm, to...@tuxteam.de wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
>
>
> On Thu, Nov 05, 2009 at 03:13:32AM -0800, Francis Moreau wrote:
> > Hello,
>
> > I'm trying to learn elisp and have a couple of basic questions.
>
> > I'm iterating over a list using dotimes, but in the body of dotimes,
> > the list can mutate. For example I have:
>
> > (dolist (elt lst)
> > ;; some codes
> > (nconc lst '(2)))
>
> > This adds/appends a new element to 'lst' list. It looks like 'dotimes'
> > doesn't like it.
>
> > So I eventually wrote it like this
>
> > (setq i 0)
> > (while (< i (length lst))
> > ;; some codes
> > (x-nconc lst '(2))))
> > (setq i (1+ i)))
>
> > which is a bit ugly, is there another way to do that ?
>
> What about:
>
> (let ((l lst))
> (while l
> (do-something-with (car l))
> (setq l (cdr l))))
>
looks better but as David pointed out, appending something to a list
is quite expensive.
> This should be fine as long as you only append to lst. Dragons might
> emerge whenever you do more drastic things to it ;-)
>
> (and you would have to re-think things when Emacs Lisp becomes
> multi-threaded. It might work then and it might not).
>
Is this going to happen ?
Thanks
next prev parent reply other threads:[~2009-11-05 14:29 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-05 11:13 Basic questions about elisp Francis Moreau
2009-11-05 11:50 ` Lennart Borgman
[not found] ` <mailman.10118.1257421858.2239.help-gnu-emacs@gnu.org>
2009-11-05 12:07 ` Francis Moreau
2009-11-05 12:44 ` Lennart Borgman
2009-11-05 12:59 ` David Kastrup
2009-11-05 14:25 ` Francis Moreau
2009-11-05 14:37 ` Pascal J. Bourguignon
2009-11-05 14:58 ` Pascal J. Bourguignon
2009-11-05 12:57 ` tomas
[not found] ` <mailman.10122.1257425638.2239.help-gnu-emacs@gnu.org>
2009-11-05 14:29 ` Francis Moreau [this message]
2009-11-05 14:41 ` Pascal J. Bourguignon
2009-11-05 15:06 ` David Kastrup
2009-11-06 16:03 ` Francis Moreau
2009-11-06 16:49 ` David Kastrup
2009-11-06 20:53 ` Francis Moreau
2009-11-06 21:18 ` Pascal J. Bourguignon
2009-11-07 14:49 ` Francis Moreau
2009-11-07 17:50 ` Pascal J. Bourguignon
2009-11-08 9:46 ` tomas
[not found] ` <mailman.10266.1257674088.2239.help-gnu-emacs@gnu.org>
2009-11-09 20:51 ` Francis Moreau
2009-11-08 15:18 ` Francis Moreau
2009-11-08 16:58 ` tomas
2009-11-08 17:12 ` Pascal J. Bourguignon
2009-11-09 21:04 ` Francis Moreau
2009-11-10 12:11 ` Joost Kremers
2009-11-10 14:16 ` Francis Moreau
2009-11-10 18:53 ` David Kastrup
2009-11-06 5:06 ` Barry Margolin
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