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: How to define a (derived) minor mode inaccessible to the user Date: Fri, 22 Jan 2021 16:23:52 +0100 Message-ID: <875z3pknav.fsf@mbork.pl> References: <87eeidlfmw.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="30151"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: mu4e 1.1.0; emacs 28.0.50 Cc: help-gnu-emacs@gnu.org To: Stefan Monnier Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane-mx.org@gnu.org Fri Jan 22 16:24:32 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 1l2yIa-0007lK-KV for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 22 Jan 2021 16:24:32 +0100 Original-Received: from localhost ([::1]:52456 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2yIZ-0001r4-MI for geh-help-gnu-emacs@m.gmane-mx.org; Fri, 22 Jan 2021 10:24:31 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]:37610) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1l2yIG-0001qu-7N for help-gnu-emacs@gnu.org; Fri, 22 Jan 2021 10:24:12 -0500 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:36388) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1l2yIA-0006UF-W8 for help-gnu-emacs@gnu.org; Fri, 22 Jan 2021 10:24:11 -0500 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id D2FC7E6707; Fri, 22 Jan 2021 16:24:00 +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 XbdAPbIWqyyo; Fri, 22 Jan 2021 16:23:56 +0100 (CET) Original-Received: from localhost (83.8.191.33.ipv4.supernova.orange.pl [83.8.191.33]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 8C01FE6490; Fri, 22 Jan 2021 16:23:56 +0100 (CET) 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:127319 Archived-At: On 2021-01-22, at 15:19, Stefan Monnier wrote: >> I'd like to define a special-purpose major mode, derived from >> `special-mode', in such a way that the user cannot set it using M-x. > > Can you explain why? Because I woulnd't like the user to accidentally turn it on? (It might be a bit of OCD on my part, too.) Also, because I didn't know how to do it and the very fact bugged me a bit;-). Also, see below. >> (It is to be called via another command.) > > That doesn't explain why it would be harmful to also expose the actual > major mode command. Maybe not harmful, but here's another argument: assume that I have this new mode, let's call it "blue-mode", with all its commands named "blue-...", and the entry point being the command "blue-display". Now, when the user says M-x blue- TAB, "blue-mode" will show up and pollute the list (meaning: it will occupy some room on the list while being useless, since blue-display is what user really wants to start using blue-mode). > E.g. You can do `M-x comint-mode` even though it likely won't do you > much good since `comint-mode` needs to be used together with a process > and is hence normally enabled by the command that launches the process. > >> It seems that `define-derived-mode' always sets the mode as >> `interactive'. > > Indeed. > >> M-: (symbol-plist 'my--mode) >> expecting an `interactive-form' entry on the plist > > The `interactive-form` property is virtually never used. Instead, the > interactive form is traditionally stored within the function. So how does `execute-extended-command' know what to list, then? A cursory look told me that it uses `read-extended-command', which uses `commandp'. So, how does `commandp' know? (I'm not well versed in C, but do I guess correctly that it checks the `interactive-form' property, and if nil, it (somehow) looks for `(interactive ...)' in its definition?) > If you *really* care about hiding the major mode from the user > I suggest you use an "obscure" or "scary" name. Well, the convention is to use two dashes, but how can the end-user (not knowing Elisp and the conventions) know that? >> What's going on? Is it possible to define a (derived) major mode so >> that it can't be called interactively? > > Of course it is: > > (define-derived-mode my-mode "My" "My doc.") > (defconst my-mode (symbol-function 'my-mode)) > (fmakunbound 'my-mode) > > and then you can enable the mode with `(funcall my-mode)`. So, basically you move the function definition from the function cell to the value cell of `my-mode', right? Clever! Is it actually used anywhere in Emacs? Thanks, -- Marcin Borkowski http://mbork.pl