From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Kangas Newsgroups: gmane.emacs.bugs Subject: bug#58513: describe-function should say that defconst variables are constant Date: Mon, 17 Oct 2022 05:41:09 +0000 Message-ID: References: <87zgdy8ug8.fsf@gnus.org> <8fae3292e6c1b175853b557060d05487@webmail.orcon.net.nz> <87v8om8tok.fsf@gnus.org> <87edva8seu.fsf@gnus.org> <87sfjq7a91.fsf@gnus.org> <875ygl5roe.fsf@gnus.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="38136"; mail-complaints-to="usenet@ciao.gmane.io" Cc: psainty@orcon.net.nz, monnier@iro.umontreal.ca, 58513@debbugs.gnu.org To: rms@gnu.org, Lars Ingebrigtsen Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Mon Oct 17 07:43:59 2022 Return-path: Envelope-to: geb-bug-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 1okIus-0009p3-OP for geb-bug-gnu-emacs@m.gmane-mx.org; 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Mon, 17 Oct 2022 05:41:09 +0000 In-Reply-To: X-Hashcash: 1:20:221017:monnier@iro.umontreal.ca::wnXHaFTqHLaKVnW5:7Vxd X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane-mx.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.io gmane.emacs.bugs:245685 Archived-At: Richard Stallman writes: > defconst has had a subtle meaning: "It is ok to expect, in certain > limited ways, that the value will not be altered." Nothing more. To my mind, the meaning is not subtle. On the contrary, it is both clear and well-documented. The manual (info "(elisp) Defining Variables") explains: [defconst] defines SYMBOL as a value and initializes it. It informs a person reading your code that SYMBOL has a standard global value, established here, that should not be changed by the user or by other programs. >From where I'm standing, this means that there is no practical difference between a defconst and a defvar that Lisp code can rely on. So, to give a somewhat contrived example, you can still break any mathematical calculation in Emacs with: (setq float-pi 9) The only way to not have your code break in the face of that is to copy-paste the literal 3.141592... everywhere.