From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: Re: Bidirectional text and URLs Date: Mon, 01 Dec 2014 05:17:58 -0500 Message-ID: References: <87a93cngwv.fsf@uwakimon.sk.tsukuba.ac.jp> <837fyfml31.fsf@gnu.org> <874mtio7wh.fsf@uwakimon.sk.tsukuba.ac.jp> <83r3wml8kq.fsf@gnu.org> <83a938aeuc.fsf@gnu.org> Reply-To: rms@gnu.org NNTP-Posting-Host: plane.gmane.org Content-Type: text/plain; charset=ISO-8859-15 X-Trace: ger.gmane.org 1417429101 30103 80.91.229.3 (1 Dec 2014 10:18:21 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 1 Dec 2014 10:18:21 +0000 (UTC) Cc: larsi@gnus.org, emacs-devel@gnu.org To: Eli Zaretskii Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Mon Dec 01 11:18:16 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 1XvO3c-0003aW-Da for ged-emacs-devel@m.gmane.org; Mon, 01 Dec 2014 11:18:16 +0100 Original-Received: from localhost ([::1]:59365 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvO3b-0006Kz-VB for ged-emacs-devel@m.gmane.org; Mon, 01 Dec 2014 05:18:15 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54416) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvO3U-0006D8-Mn for emacs-devel@gnu.org; Mon, 01 Dec 2014 05:18:09 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XvO3T-0002YL-8z for emacs-devel@gnu.org; Mon, 01 Dec 2014 05:18:08 -0500 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:50438) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XvO3T-0002YH-6r for emacs-devel@gnu.org; Mon, 01 Dec 2014 05:18:07 -0500 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.71) (envelope-from ) id 1XvO3K-0005rt-O6; Mon, 01 Dec 2014 05:17:59 -0500 In-reply-to: <83a938aeuc.fsf@gnu.org> (message from Eli Zaretskii on Sun, 30 Nov 2014 17:27:23 +0200) X-detected-operating-system: by eggs.gnu.org: Error: Malformed IPv6 address (bad octet value). X-Received-From: 2001:4830:134:3::e 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:178571 Archived-At: [[[ To any NSA and FBI agents reading my email: please consider ]]] [[[ whether defending the US Constitution against all enemies, ]]] [[[ foreign or domestic, requires you to follow Snowden's example. ]]] We need to make Emacs safe and clear for users who don't know anything about bidi and don't want to. One idea: change the mode line color when there is any RTL text (in the buffer, or on the screen, whichever is easier). Another idea: make magic bidi characters visible by default. People who edit in RTL languages and get used to bidi could set a user option to make them invisible. > This is the first time I've observe RTL display in Emacs. I don't see > any way to detect the magic character that specifies it. That's because there isn't one, in the citation you provided. Yes there was -- you said so yourself: > where there is a u+202e character The point is that I could not tell what it was, or where it was, or anything about it, from my ordinary Emacs commands -- even though I knew I was observing RTL text display and that some magic bidi character was probably the reason for it. Plenty of users wouldn't even know that much. at the rightmost (visual) edge of > the line. If you move point with C-f from the beginning of that line, > you should see it jump to the right edge of the line after the leading > whitespace, and then continue to "advance backwards", i.e. to the left. Yes, I observed that strange behavior. As I said, it was the first time I saw Emacs's bidi display functionality actually operate. But I could not tell how to detect the presence of that the magic character directly. I could see the bidi effect, but I could not tell what was causing it. > These characters are by default displayed as spaces on a TTY, and as a > very thin (1-pixel) space on GUI frames. > > I think we need to provide a way to make them visible. > We already have it: the glyphless-char-display char-table. We need a convenient _user-level_ feature to make them visible. > I don't think so: these controls should normally be all but invisible. We need to make it easy to see them. Otherwise people can't tell why strangeness is happening on their screens. > > Also, is there a way to disable bidi in the current buffer? > > If not, I think we need one. > There is a way, but it is not meant for Lisp programs, only for > debugging the display engine. It needs to be made convenient for users. Especially for users who never use bidi. You use an RTL language, so you see bidi text often and it doesn't surprise you. When you see it, you know what is going on. You know what in the buffer is likely to cause what visual results. I don't speak any RTL language (and those characters won't display on this tty anyway). So I never see bidi at work, or at least not in a way I would notice. I get mail that might be in Arabic script, but that's just a guess. The messages are spam, so I delete them. Even so, I am more knowledgeable about bidi than most Emacs users. I once read the the Unicode bidi rules, I just don't remember them. I think most Emacs users have even less knowledge of this issue. We need to make Emacs safe and clear for users who don't know anything about bidi and don't want to. -- Dr Richard Stallman President, Free Software Foundation 51 Franklin St Boston MA 02110 USA www.fsf.org www.gnu.org Skype: No way! That's nonfree (freedom-denying) software. Use Ekiga or an ordinary phone call.