From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Forbid reverse ranges in rx Date: Tue, 12 Mar 2019 12:56:40 -0400 Message-ID: References: <50fb83052c1de4da59f0a857deed2e5d9e533c13.camel@acm.org> <458975ce0c15165e6a6e62cbda75c8b912a59d8f.camel@acm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="70916"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Mar 12 18:10:12 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1h3kup-000IJx-JR for ged-emacs-devel@m.gmane.org; Tue, 12 Mar 2019 18:10:11 +0100 Original-Received: from localhost ([127.0.0.1]:56080 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h3kuo-0007EQ-FR for ged-emacs-devel@m.gmane.org; Tue, 12 Mar 2019 13:10:10 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:45949) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h3khv-0004wd-C2 for emacs-devel@gnu.org; Tue, 12 Mar 2019 12:56:52 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h3khu-0003qG-8E for emacs-devel@gnu.org; Tue, 12 Mar 2019 12:56:51 -0400 Original-Received: from [195.159.176.226] (port=37424 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h3kht-0003oE-Ny for emacs-devel@gnu.org; Tue, 12 Mar 2019 12:56:49 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.89) (envelope-from ) id 1h3khr-0000t1-UD for emacs-devel@gnu.org; Tue, 12 Mar 2019 17:56:47 +0100 X-Injected-Via-Gmane: http://gmane.org/ Cancel-Lock: sha1:JhS8yNcrppPGa/IbA2sbUm1LGU4= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:234111 Archived-At: >> > + (error "Reverse range `%c-%c' in Rx `any' >> > not permitted" >> > + start end))) >> >> Consider rephrasing this to explain why it's not permitted (maybe "… >> no permitted, as it does not match anything"). > > Do we really need to mention the legacy semantics, which were > accidental and arbitrary? "Z-A" is disallowed because it doesn't make > sense, not because of what happened before we thought of checking. Indeed, I don't think we need to explain in detail, but I think it's likely that the naive user will simply not understand "reverse range". Maybe instead of saying it's not permitted, we should say "range %c-%c is reversed"? Stefan