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] : What is the difference between (deactivate-mark) and (setq deactivate-mark t)? Date: Wed, 07 Apr 2021 07:14:20 +0200 Message-ID: <87v98ybrrn.fsf@mbork.pl> References: <87pmzc825q.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="2727"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 28.0.50 Cc: Help Gnu Emacs mailing list To: Drew Adams Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Wed Apr 07 07:16:19 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 1lU0Y7-0000Yi-6p for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 07 Apr 2021 07:16:19 +0200 Original-Received: from localhost ([::1]:33682 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lU0Y6-00060Q-8H for geh-help-gnu-emacs@m.gmane-mx.org; Wed, 07 Apr 2021 01:16:18 -0400 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:41120) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lU0XD-00060H-5u for help-gnu-emacs@gnu.org; Wed, 07 Apr 2021 01:15:23 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:47486) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lU0X5-0002yE-6d for help-gnu-emacs@gnu.org; Wed, 07 Apr 2021 01:15:22 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id 8D0E9E6DCC; Wed, 7 Apr 2021 07:15:05 +0200 (CEST) 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 yK3xbIgDyMud; Wed, 7 Apr 2021 07:14:56 +0200 (CEST) Original-Received: from localhost (178235147101.dynamic-3-poz-k-0-1-0.vectranet.pl [178.235.147.101]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 52798E64B3; Wed, 7 Apr 2021 07:14:25 +0200 (CEST) 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 autolearn=ham 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:128881 Archived-At: On 2021-04-03, at 06:11, Drew Adams wrote: >> Well, I understand what each of them does, but whay was the variable >> introduced and why would I want to say `(setq deactivate-mark t)' in >> a command instead of just calling `(deactivate-mark)'? I can't think of >> any possible reasons. Any ideas? > > I may be repeating what you say you already > understand, but... > > Function `deactivate-mark' deactivates the mark > (duh), and it does so right away. > > After a command finishes and returns, the command > loop normally automatically deactivates the mark. > IOW, for the next command the mark is inactive. Well, I don't think that's the case. Take this command: (defun petrichor () (interactive) (message "Smell of the dust after the rain")) activate the region and say M-x petrichor - the region is still active. If I want to change this, I can either say `(deactivate-mark)' or `(setq deactivate-mark t)'. My question was, why I would want to choose the latter? I think I now know the reason - while experimenting with this and studying the docs, I probably found out. Can anyone correct me if I'm wrong? It seems that its main use is to actually _prevent_ the code from deactivating the region _if_ it would do it otherwise, by means of _modifying_ the buffer. Since every primitive that changes the buffer (like `insert') sets it to `t', you can say `(setq deactivate-mark nil)` at the end of a buffer-modifying command and the region will remain active if it was before running it. (The manual suggests temporarily binding it with `let' which has a similar effect, as you mentioned.) Does that make sense? -- Marcin Borkowski http://mbork.pl