From mboxrd@z Thu Jan 1 00:00:00 1970 Path: main.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.help Subject: Re: replacing a certain element in a list with another Date: 30 Sep 2003 11:05:58 +0200 Organization: Organization?!? Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Message-ID: References: NNTP-Posting-Host: deer.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1064913882 17967 80.91.224.253 (30 Sep 2003 09:24:42 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 30 Sep 2003 09:24:42 +0000 (UTC) Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Tue Sep 30 11:24:40 2003 Return-path: Original-Received: from monty-python.gnu.org ([199.232.76.173]) by deer.gmane.org with esmtp (Exim 3.35 #1 (Debian)) id 1A4GkK-0007dZ-00 for ; Tue, 30 Sep 2003 11:24:40 +0200 Original-Received: from localhost ([127.0.0.1] helo=monty-python.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.22) id 1A4Gbu-00044f-6J for geh-help-gnu-emacs@m.gmane.org; Tue, 30 Sep 2003 05:15:58 -0400 Original-Path: shelby.stanford.edu!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!fu-berlin.de!uni-berlin.de!p3ee20b9d.dip.t-dialin.NET!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 40 Original-NNTP-Posting-Host: p3ee20b9d.dip.t-dialin.net (62.226.11.157) Original-X-Trace: news.uni-berlin.de 1064912758 10522696 62.226.11.157 (16 [198409]) X-Face: 2FEFf>]>q>2iw=B6, xrUubRI>pR&Ml9=ao@P@i)L:\urd*t9M~y1^:+Y]'C0~{mAl`oQuAl \!3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN; i"; /yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi$t^ Vc\LWP@J5p^rst0+('>Er0=^1{]M9!p?&:\z]|;&=NP3AhB!B_bi^]Pfkw User-Agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3.50 Original-Xref: shelby.stanford.edu gnu.emacs.help:116955 Original-To: help-gnu-emacs@gnu.org X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.2 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: main.gmane.org gmane.emacs.help:12881 X-Report-Spam: http://spam.gmane.org/gmane.emacs.help:12881 Klaus Berndl writes: > Suppose i have the following list: > > '(a b c d) > > What is a good way to replace one of the list-elements with another, so foe > example replacing the 'c with 'e? > But: i do not want using any c-functions, so i would prefer a > solution without using `substitute'! Uh, what? Anyhow, try (let ((xxx '(a b c d))) (setcar (member 'c xxx) 'e) xxx) > Is the solution easier if i always want to replace the last element > of the list? Not really. > I think so, because it could be: > > (defvar my-list '( a b c d)) > > (let ((temp-l (nreverse my-list))) > (setcar temp-l 'e) > (nreverse temp-l)) > > Is this a good elisp-solution? No. Runs through the list quite more often than necessary, and leaves my-list in a pretty undefined state. -- David Kastrup, Kriemhildstr. 15, 44793 Bochum