From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.help Subject: Re: [External] : Re: Is there a way of setting a variable only when it exists? Date: Wed, 16 Mar 2022 19:32:35 +0100 Message-ID: <87y219u4sc.fsf@mbork.pl> References: <87lexdul8e.fsf@mbork.pl> <878rtcir1h.fsf@zoho.eu> <87a6drviwp.fsf@mbork.pl> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="12470"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 29.0.50 Cc: "help-gnu-emacs@gnu.org" , Emanuel Berg To: Drew Adams Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Mar 16 19:34:43 2022 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 1nUYTq-00030g-32 for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 16 Mar 2022 19:34:42 +0100 Original-Received: from localhost ([::1]:38146 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUYTo-0000Me-L0 for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 16 Mar 2022 14:34:40 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:35974) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUYSO-0000M8-Ov for help-gnu-emacs@gnu.org; Wed, 16 Mar 2022 14:33:15 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:51606) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUYSG-000666-6f for help-gnu-emacs@gnu.org; Wed, 16 Mar 2022 14:33:10 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id 3341AE70F3; Wed, 16 Mar 2022 19:32:39 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JBHYbLQWbGIw; Wed, 16 Mar 2022 19:32:35 +0100 (CET) Original-Received: from localhost (83.8.166.110.ipv4.supernova.orange.pl [83.8.166.110]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 85ABFE653B; Wed, 16 Mar 2022 19:32:35 +0100 (CET) In-reply-to: Received-SPF: pass client-ip=195.110.48.8; envelope-from=mbork@mbork.pl; helo=mail.mojserwer.eu X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.29 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:136612 Archived-At: On 2022-03-15, at 16:38, Drew Adams wrote: >> What if it's an internal Emacs variable which might become a user >> option one day (I submitted a bug report about it) and then my >> customization silently disappears? It's the "silently" part I >> want to guard against... > > What do you mean by "an internal Emacs variable"? As I hinted in my question, one whose name contains a double dash. > If it's a defvar then Emacs's predefined defvar > has no effect if you defvar the variable before > Emacs does. And it has no effect if you setq > the var before or after Emacs defvars it (as long > as Emacs doesn't _use_ it before you setq it). I know that. > If Emacs later changes it to a defcustom, the > same things apply. However, if the defcustom has > a :set function then your own setting of it might > no longer be appropriate ("valid"). If, however, it gets promoted to a user option - and gets renamed - things look different. Best, -- Marcin Borkowski http://mbork.pl