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: Is there a way of setting a variable only when it exists? Date: Mon, 14 Mar 2022 07:00:33 +0100 Message-ID: <87lexdul8e.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="14966"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 29.0.50 To: Help Gnu Emacs mailing list Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Mon Mar 14 07:01:48 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 1nTdm7-0003hm-PC for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 14 Mar 2022 07:01:47 +0100 Original-Received: from localhost ([::1]:40280 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nTdm6-0000MN-F7 for geh-help-gnu-emacs@m.gmane-mx.org; Mon, 14 Mar 2022 02:01:46 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:60046) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nTdlB-0000K4-Vd for help-gnu-emacs@gnu.org; Mon, 14 Mar 2022 02:00:50 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:45646) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nTdl7-0007K3-OO for help-gnu-emacs@gnu.org; Mon, 14 Mar 2022 02:00:48 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id A3A9DE70B0 for ; Mon, 14 Mar 2022 07:00:40 +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 H1_N5igeEzT0 for ; Mon, 14 Mar 2022 07:00:37 +0100 (CET) Original-Received: from localhost (178235147010.dynamic-3-poz-k-0-1-0.vectranet.pl [178.235.147.10]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 41BF0E653B for ; Mon, 14 Mar 2022 07:00:37 +0100 (CET) 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:136530 Archived-At: Hi all, I'd like to be able to say something like (setq-safe hello "world") so that `hello' is set to `"world"' if it is an existing variable (e.g., defined by `defvar') and an error is raised if `hello' does not exist. Rationale: I'm setting an internal Emacs variable. At the same time, I submitted a feature request to turn it into a user option, so that it's possible that in a future version of Emacs it's going to change its name (it has two dashes in it). I want to be warned then that I need to change my `init.el' accordingly. I assume it would be fairly easy to code such a macro (using `boundp'), but maybe it exists already? TIA, -- Marcin Borkowski http://mbork.pl