From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg via Users list for the GNU Emacs text editor Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Appending lists Date: Mon, 21 Jun 2021 00:54:58 +0200 Message-ID: <87im28f8ot.fsf@zoho.eu> 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> <87pmwgfehh.fsf@zoho.eu> Reply-To: Emanuel Berg 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="37394"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:7C6El9ioWm7iTYxv/x7UkZXcFzA= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Mon Jun 21 00:55:41 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 1lv6Lt-0009YQ-7z for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 21 Jun 2021 00:55:41 +0200 Original-Received: from localhost ([::1]:48816 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lv6Lr-00030z-TP for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Jun 2021 18:55:39 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:51354) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv6LP-0002zz-Pv for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 18:55:11 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]:34072) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv6LO-0002eu-2P for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 18:55:11 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1lv6LL-0008v9-Rk for help-gnu-emacs@gnu.org; Mon, 21 Jun 2021 00:55:07 +0200 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never Received-SPF: pass client-ip=116.202.254.214; envelope-from=geh-help-gnu-emacs@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=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:131121 Archived-At: Jean Louis wrote: >> (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) <-- the tail has changed >> (setcar list-head 1.5) >> whole-list ; <-- but here, the head is still unaffected, (1 2 3.5 4) >> (setcar whole-list 1.33) ; well, of course that will work... >> whole-list ; (1.33 2 3.5 4) >> list-head ; still (1.5) > > (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) ; (3.5 4) > It did not change now: > whole-list ⇒ (1 2 3 4) ; (1 2 3.5 4) <-- the tail has changed But here it did again, despite `copy-sequence'! (progn (setq list-head '(1)) (setq list-tail '(2 3 4)) (setq list-tail-2 (copy-sequence list-tail)) (setq whole-list (append list-head list-tail-2)) (setcdr list-tail-2 '(3.5 4)) whole-list ) ; (1 2 3.5 4) Oh, no! -- underground experts united https://dataswamp.org/~incal