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: Sun, 30 Nov 2014 17:20:11 +0200 Message-ID: <83egskaf6c.fsf@gnu.org> References: <87zjbbdt0u.fsf@igel.home> <833892aq3m.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: plane.gmane.org X-Trace: ger.gmane.org 1417360847 17291 80.91.229.3 (30 Nov 2014 15:20:47 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 30 Nov 2014 15:20:47 +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 Sun Nov 30 16:20:38 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 1Xv6If-0005i7-RS for ged-emacs-devel@m.gmane.org; Sun, 30 Nov 2014 16:20:37 +0100 Original-Received: from localhost ([::1]:50718 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xv6If-000498-CR for ged-emacs-devel@m.gmane.org; Sun, 30 Nov 2014 10:20:37 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:50161) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xv6IJ-000493-Pw for emacs-devel@gnu.org; Sun, 30 Nov 2014 10:20:21 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xv6IE-0001XW-E2 for emacs-devel@gnu.org; Sun, 30 Nov 2014 10:20:15 -0500 Original-Received: from mtaout23.012.net.il ([80.179.55.175]:45799) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xv6IE-0001XG-6H; Sun, 30 Nov 2014 10:20:10 -0500 Original-Received: from conversion-daemon.a-mtaout23.012.net.il by a-mtaout23.012.net.il (HyperSendmail v2007.08) id <0NFU00600YFZK800@a-mtaout23.012.net.il>; Sun, 30 Nov 2014 17:20:08 +0200 (IST) Original-Received: from HOME-C4E4A596F7 ([87.69.4.28]) by a-mtaout23.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0NFU006GGYLK4AA0@a-mtaout23.012.net.il>; Sun, 30 Nov 2014 17:20:08 +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: 80.179.55.175 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:178517 Archived-At: > Date: Sun, 30 Nov 2014 04:38:04 -0500 > From: Richard Stallman > CC: schwab@linux-m68k.org, larsi@gnus.org, emacs-devel@gnu.org > > > > 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, > > I think we are talking about different issues. You're talking about > whether Lisp programs control the directionality. I'm talking about > providing a way for them to inquire what display will do. I apologize for my misunderstanding. > > > 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. > > I suggest the definition: whatever would cause the displayed order of > characters to be perhaps misleading if the text is interpreted as a > URL or anything else with programatic significance. I'm sorry, but this is not instrumental: it doesn't specify what "misleading" means. We need a detailed spec for that. The underlying problem here is that many cases of what readers of RTL scripts will perceive as perfectly valid reordering might appear "misleading" to people who don't read those scripts. We should strive to arrive at a definition that detects unreasonable and suspicious reordering, not just any reordering. One possible definitions for "misleading" were suggested earlier: strict left-to-right text which is reordered for display due to directional control characters. If this is what we want, I can work on providing infrastructure for detecting these cases (and perhaps also similar ones for when similar games are played with URLs that use RTL characters). If that is not what we want, then we need to continue discussing the requirements.