From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Jean Louis Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Appending lists Date: Mon, 21 Jun 2021 00:46:01 +0300 Message-ID: References: <20210617074843.GD16310@tuxteam.de> <87r1gy3f70.fsf@zoho.eu> <20210619065703.GB29866@tuxteam.de> <87fsxdzgl9.fsf@zoho.eu> <87im28gvsx.fsf@zoho.eu> <87tulsfeuf.fsf@zoho.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="18785"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Mutt/2.0.7+183 (3d24855) (2021-05-28) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Sun Jun 20 23:48:25 2021 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1lv5Im-0004fs-NH for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Jun 2021 23:48:24 +0200 Original-Received: from localhost ([::1]:60708 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lv5Ik-0004N8-Ue for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Jun 2021 17:48:22 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:41056) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv5IK-0004N0-Hf for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 17:47:56 -0400 Original-Received: from stw1.rcdrun.com ([217.170.207.13]:59547) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv5II-0000tx-Qy for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 17:47:56 -0400 Original-Received: from localhost ([::ffff:197.157.0.61]) (AUTH: PLAIN admin, TLS: TLS1.3,256bits,ECDHE_RSA_AES_256_GCM_SHA384) by stw1.rcdrun.com with ESMTPSA id 00000000000D993F.0000000060CFB788.00007692; Sun, 20 Jun 2021 14:47:51 -0700 Mail-Followup-To: help-gnu-emacs@gnu.org Content-Disposition: inline In-Reply-To: <87tulsfeuf.fsf@zoho.eu> Received-SPF: pass client-ip=217.170.207.13; envelope-from=bugs@gnu.support; helo=stw1.rcdrun.com X-Spam_score_int: 29 X-Spam_score: 2.9 X-Spam_bar: ++ X-Spam_report: (2.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_SBL_CSS=3.335, RCVD_IN_SORBS_WEB=1.5, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.23 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-mx.org@gnu.org Original-Sender: "help-gnu-emacs" Xref: news.gmane.io gmane.emacs.help:131117 Archived-At: * Emanuel Berg via Users list for the GNU Emacs text editor [2021-06-20 23:43]: > Actually `append' can also be trouble because the last list > isn't copied, the new list just has a cdr somewhere to it - > yes, to the actual list. > > Try this: > > (setq list-head '(1)) ; (1) > > (setq list-tail '(2 3 4)) ; (2 3 4) > > (setq whole-list (append list-head list-tail)) ; (1 2 3 4) > > (setcdr list-tail '(3.5 4)) ; (3.5 4) > > whole-list ; (1 2 3.5 4) > > See that "whole-list" changed even tho we did it with `setq', > append, and didn't mention it... I see. I wonder if there are some implications in my code. Though I never used `setcdr' in that combination (or never). Maybe this is the way to go: (setq list-head '(1)) ⇒ (1) (setq list-tail '(2 3 4)) ⇒ (2 3 4) (setq whole-list (append list-head (copy-sequence list-tail))) ⇒ (1 2 3 4) (setcdr list-tail '(3.5 4)) ⇒ (3.5 4) whole-list ⇒ (1 2 3 4) -- Jean Take action in Free Software Foundation campaigns: https://www.fsf.org/campaigns In support of Richard M. Stallman https://stallmansupport.org/