From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Bidirectional text and URLs Date: Sat, 29 Nov 2014 19:11:57 +0200 Message-ID: <833892aq3m.fsf@gnu.org> References: <87zjbbdt0u.fsf@igel.home> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1417281143 17043 80.91.229.3 (29 Nov 2014 17:12:23 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 29 Nov 2014 17:12:23 +0000 (UTC) Cc: larsi@gnus.org, schwab@linux-m68k.org, emacs-devel@gnu.org To: rms@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Nov 29 18:12:16 2014 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1XulZ9-000333-Ud for ged-emacs-devel@m.gmane.org; Sat, 29 Nov 2014 18:12:16 +0100 Original-Received: from localhost ([::1]:48290 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XulZ9-0007N4-CJ for ged-emacs-devel@m.gmane.org; Sat, 29 Nov 2014 12:12:15 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:48433) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XulZ0-0007Mi-Hd for emacs-devel@gnu.org; Sat, 29 Nov 2014 12:12:12 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XulYs-0000cZ-HW for emacs-devel@gnu.org; Sat, 29 Nov 2014 12:12:06 -0500 Original-Received: from mtaout22.012.net.il ([80.179.55.172]:34102) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XulYs-0000bz-9S; Sat, 29 Nov 2014 12:11:58 -0500 Original-Received: from conversion-daemon.a-mtaout22.012.net.il by a-mtaout22.012.net.il (HyperSendmail v2007.08) id <0NFT00H008ZERZ00@a-mtaout22.012.net.il>; Sat, 29 Nov 2014 19:11:57 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([87.69.4.28]) by a-mtaout22.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0NFT00H9293W7K80@a-mtaout22.012.net.il>; Sat, 29 Nov 2014 19:11:57 +0200 (IST) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by eggs.gnu.org: Solaris 10 X-Received-From: 80.179.55.172 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.14 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-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:178463 Archived-At: > Date: Sat, 29 Nov 2014 12:04:17 -0500 > From: Richard Stallman > Cc: larsi@gnus.org, emacs-devel@gnu.org > > > The RTL flag character in the example isn't part of the URL, it only > > precedes it. > > (I couldn't see it in any case.) It's displayed as a very thin space. > This suggests we need to provide a primitive to tell Lisp programs a > guaranteed answer for which direction the text at a certain point is > displayed in. The directionality of the text is determined by the display engine, and by design is not subject to control by Lisp programs, with 2 notable exceptions (none of which are relevant to the issue at hand): . Lisp programs can disable bidi reordering in a buffer . Lisp programs can define the base paragraph direction > Also, a primitive to verify that a certain region of text has no > bidi strangeness within it. We need to have a good instrumental definition of "bidi strangeness" for that. The simple job of determining whether the region of text includes RTL characters or bidi formatting controls is already possible by using suitable regular expressions, of course. > On issues like this, better safe than sorry. The user who wants to > override the safety measure can easily do that. For instance, > inserting line breaks around the URL would make it be considered safe, > right? No. In fact, it won't change at all the (jumbled) display of the example presented by Lars.