From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Emanuel Berg via Users list for the GNU Emacs text editor Newsgroups: gmane.emacs.help Subject: Re: Understanding the "let" construct and the setting of variables Date: Fri, 18 Dec 2020 21:46:38 +0100 Message-ID: <87wnxeyh8x.fsf@zoho.eu> References: <87zh2d1byp.fsf@fastmail.fm> <87o8is26nu.fsf@fastmail.fm> Reply-To: Emanuel Berg Mime-Version: 1.0 Content-Type: text/plain Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="27654"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) To: help-gnu-emacs@gnu.org Cancel-Lock: sha1:UL3GAkYr4UXJPDD8Q4NPfgsgn5A= Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Dec 18 21:48:10 2020 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 1kqMfa-000744-I8 for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 18 Dec 2020 21:48:10 +0100 Original-Received: from localhost ([::1]:45286 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kqMfZ-0006N4-LR for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 18 Dec 2020 15:48:09 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:54142) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kqMeF-0005WS-Fa for help-gnu-emacs@gnu.org; Fri, 18 Dec 2020 15:46:47 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]:58794) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kqMeD-0000T1-UU for help-gnu-emacs@gnu.org; Fri, 18 Dec 2020 15:46:47 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1kqMeC-0005NQ-4H for help-gnu-emacs@gnu.org; Fri, 18 Dec 2020 21:46:44 +0100 X-Injected-Via-Gmane: http://gmane.org/ Mail-Followup-To: help-gnu-emacs@gnu.org Mail-Copies-To: never 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: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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:126529 Archived-At: steve-humphreys wrote: > This gets me to "defvar". I have read that "setq" does net > actually make a variable. It is defvar that makes a variable > available. When reading the "Intro to Emacs Lisp", the focus > is on using "setq". `setq' is enough, it does the real job alright, but the byte-compiler will complain if there isn't a `defvar' before it. Also with defvar you can set a default value and add a docstring. None of that is mandatory and the default value can even be confusing IMO. Just think of defvar as a way of telling Emacs and everyone else, "I intend to use a variable with this name." This is enough, and always do it (_at least_ do that, of course by all means set the default and add a docstring if that fancies you), but always and at least do this: (defvar some-var) (setq some-var some-value) That's enough. You have what you need and the byte-compiler doesn't complain. -- underground experts united http://user.it.uu.se/~embe8573 https://dataswamp.org/~incal