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: Sun, 20 Jun 2021 22:59:10 +0300 Message-ID: References: <20210617074843.GD16310@tuxteam.de> <87r1gy3f70.fsf@zoho.eu> <20210619065703.GB29866@tuxteam.de> <87fsxdzgl9.fsf@zoho.eu> <87im28gvsx.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="20690"; 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 22:02:55 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 1lv3eg-00056O-8C for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Jun 2021 22:02:54 +0200 Original-Received: from localhost ([::1]:58940 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lv3ef-0002lY-4V for geh-help-gnu-emacs@m.gmane-mx.org; Sun, 20 Jun 2021 16:02:53 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:56366) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv3de-0002lB-En for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 16:01:53 -0400 Original-Received: from stw1.rcdrun.com ([217.170.207.13]:34871) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lv3dc-0000Hu-K8 for help-gnu-emacs@gnu.org; Sun, 20 Jun 2021 16:01:50 -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 00000000000D993D.0000000060CF9EA9.000046A2; Sun, 20 Jun 2021 13:01:45 -0700 Mail-Followup-To: help-gnu-emacs@gnu.org Content-Disposition: inline In-Reply-To: <87im28gvsx.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:131109 Archived-At: * Emanuel Berg via Users list for the GNU Emacs text editor [2021-06-20 22:51]: > After this discussion, I thought I'd examine my `nconc' once > more and I then realized my use of them resembles a functional > style, while it (nconc) is already destructively doing the > updating, so that's not needed. E.g., this > > ;; (setq completion-ignored-extensions > ;; (nconc completion-ignored-extensions '(".bcf" ".elc" ".run.xml")) ) > > can be changed into (should be changed, since the above makes > no difference - ?) it can be changed into > > (nconc completion-ignored-extensions '(".bcf" ".run.xml")) I would use it this way: (setq completion-ignored-extensions (append completion-ignored-extensions '(".bcf" ".run.xml"))) As that follows the habit and logic I am personally used to. It is style preference. I like that previous variables stay the same: (setq list-a '(1 2 3)) ⇒ (1 2 3) (setq list-b '(a b c)) ⇒ (a b c) (append list-a list-b) ⇒ (1 2 3 a b c) list-a ⇒ (1 2 3) list-b ⇒ (a b c) But then I can use the previously defined variables to define a new one: (setq appended (append list-a list-b)) ⇒ (1 2 3 a b c) and nothing changed in those: list-a ⇒ (1 2 3) list-b ⇒ (a b c) while using function `nconc' would give me a habit that I rather find detrimental or not pleasing: (nconc appended list-a list-b) ⇒ (1 2 3 a b c 1 2 3 a b c . #6) list-a ⇒ (1 2 3 a b c 1 2 3 a b c . #6) list-b ⇒ (a b c 1 2 3 a b c 1 2 3 . #6) Question is why do I need to change other lists if all what I want is to set the first variable `appended' to someting new? So if I don't need to change other variables I will not use `nconc' and rather use function `append' -- Jean Take action in Free Software Foundation campaigns: https://www.fsf.org/campaigns In support of Richard M. Stallman https://stallmansupport.org/