From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Michael Heerdegen Newsgroups: gmane.emacs.help Subject: Re: Is there a way of setting a variable only when it exists? Date: Wed, 16 Mar 2022 01:47:44 +0100 Message-ID: <875yoe3eq7.fsf@web.de> 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="4643"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:R08wKKDmYryNk3LxUx5gsXrH4NE= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Mar 16 01:48:54 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 1nUHqQ-00011c-Fs for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 16 Mar 2022 01:48:54 +0100 Original-Received: from localhost ([::1]:56458 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nUHqP-0004Yf-5V for geh-help-gnu-emacs@m.gmane-mx.org; Tue, 15 Mar 2022 20:48:53 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:37426) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUHpT-0004Ww-Um for help-gnu-emacs@gnu.org; Tue, 15 Mar 2022 20:47:56 -0400 Original-Received: from ciao.gmane.io ([116.202.254.214]:50336) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nUHpS-0002LC-Ba for help-gnu-emacs@gnu.org; Tue, 15 Mar 2022 20:47:55 -0400 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1nUHpQ-000AGC-4z for help-gnu-emacs@gnu.org; Wed, 16 Mar 2022 01:47:52 +0100 X-Injected-Via-Gmane: http://gmane.org/ 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: -13 X-Spam_score: -1.4 X-Spam_bar: - X-Spam_report: (-1.4 / 5.0 requ) BAYES_00=-1.9, FREEMAIL_FORGED_FROMDOMAIN=0.249, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no 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:136599 Archived-At: 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? Michael.