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: Is there a way of setting a variable only when it exists? Date: Wed, 16 Mar 2022 19:33:49 +0100 Message-ID: <87v8wdu4qa.fsf@mbork.pl> References: <87lexdul8e.fsf@mbork.pl> <878rtcir1h.fsf@zoho.eu> <87a6drviwp.fsf@mbork.pl> <875yoe3eq7.fsf@web.de> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="20514"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 29.0.50 Cc: help-gnu-emacs@gnu.org To: Michael Heerdegen Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Mar 16 19:36:07 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 1nUYVD-0005Cn-5g for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 16 Mar 2022 19:36:07 +0100 Original-Received: from localhost ([::1]:38906 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUYVC-0000uF-3x for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 16 Mar 2022 14:36:06 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:36198) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUYTG-0000fF-Kc for help-gnu-emacs@gnu.org; Wed, 16 Mar 2022 14:34:06 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:51640) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUYTE-0006CI-Rc for help-gnu-emacs@gnu.org; Wed, 16 Mar 2022 14:34:06 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id B8C1BE70F3; Wed, 16 Mar 2022 19:34:02 +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 C_yV9f9wbLaC; Wed, 16 Mar 2022 19:33:49 +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 6587EE653B; Wed, 16 Mar 2022 19:33:49 +0100 (CET) In-reply-to: <875yoe3eq7.fsf@web.de> 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:136613 Archived-At: On 2022-03-16, at 01:47, Michael Heerdegen wrote: > Marcin Borkowski writes: > >> 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? > > That normally does not happen. `defcustom' doesn't alter existing > bindings. You can still `setq' a user option. There is no problem > unless the "meaning" of the variable values changed in an backward > incompatible way. I guess nothing can protect against that. > > The only notable case I can think of is when things change so that > setting the variable doesn't have the expected effect any more because > the custom setter has gotten additional side effects (more than only > setting the value). Is that your concern? No, my concern is the variable changing its _name_. -- Marcin Borkowski http://mbork.pl