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: arrow keys vs. C-f/b/n/p Date: Sat, 12 Jun 2010 21:49:21 +0300 Message-ID: <83k4q4jdce.fsf@gnu.org> References: <87d3w2ncqs.fsf_-_@lola.goethe.zz> <87iq5py7xk.fsf@stupidchicken.com> <83eigclgf0.fsf@gnu.org> <89C16A134A024399A06EFE296DC6916F@us.oracle.com> <83r5kcjkpp.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: lo.gmane.org X-Trace: dough.gmane.org 1276369099 22997 80.91.229.12 (12 Jun 2010 18:58:19 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Sat, 12 Jun 2010 18:58:19 +0000 (UTC) Cc: emacs-devel@gnu.org To: Drew Adams Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Jun 12 20:58:18 2010 connect(): No such file or directory Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ONVu4-0001jw-92 for ged-emacs-devel@m.gmane.org; Sat, 12 Jun 2010 20:58:17 +0200 Original-Received: from localhost ([127.0.0.1]:57784 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ONVqa-0002tm-0X for ged-emacs-devel@m.gmane.org; Sat, 12 Jun 2010 14:54:24 -0400 Original-Received: from [140.186.70.92] (port=38101 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1ONVnS-0001tI-Lp for emacs-devel@gnu.org; Sat, 12 Jun 2010 14:54:18 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1ONVmn-0007GX-OH for emacs-devel@gnu.org; Sat, 12 Jun 2010 14:50:30 -0400 Original-Received: from mtaout23.012.net.il ([80.179.55.175]:56330) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1ONVmj-0007GD-14 for emacs-devel@gnu.org; Sat, 12 Jun 2010 14:50:29 -0400 Original-Received: from conversion-daemon.a-mtaout23.012.net.il by a-mtaout23.012.net.il (HyperSendmail v2007.08) id <0L3X0060005WN800@a-mtaout23.012.net.il> for emacs-devel@gnu.org; Sat, 12 Jun 2010 21:49:21 +0300 (IDT) Original-Received: from HOME-C4E4A596F7 ([77.127.88.125]) by a-mtaout23.012.net.il (HyperSendmail v2007.08) with ESMTPA id <0L3X004C00A8AW80@a-mtaout23.012.net.il>; Sat, 12 Jun 2010 21:49:21 +0300 (IDT) In-reply-to: X-012-Sender: halo1@inter.net.il X-detected-operating-system: by eggs.gnu.org: Solaris 10 (beta) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:125833 Archived-At: > From: "Drew Adams" > Date: Sat, 12 Jun 2010 10:12:04 -0700 > Cc: emacs-devel@gnu.org > > But I think you should also make it clear (clearer) that this "logical" order > corresponds to buffer position I did: Emacs stores right-to-left and bidirectional text in the so-called "logical" (or "reading") order: the buffer or string position of the first character you read precedes that of the next character. > In fact, you might drop "logical" altogether - the word itself doesn't really > help here. This term is widely used in literature about editing bidirectional text. > And changing "character position" to "buffer position" would help. See above: the text does talk about buffer positions. > What I got from your mail yesterday, which I think is clear there, is that (a) > the buffer text stays put, regardless of how it might be displayed (I already > supposed that), and (b) cursor movement always follows buffer order: forward > means toward eob; backward means toward bob. > > It is (b) that is not so clear from the doc. That notion of "logical" movement > (movement along the buffer-position gradient) is important to understand. The manual does touch on that: Because characters are reordered for display, Emacs commands that operate in the logical order or on stretches of buffer positions may produce unusual effects. For example, `C-f' and `C-b' commands move point in the logical order, so the cursor will sometimes jump when point traverses reordered bidirectional text. Similarly, a highlighted region covering a contiguous range of character positions may look discontinuous if the region spans reordered text. This is normal and similar to behavior of other programs that support bidirectional text. > Admittedly, it can be tricky to talk about these things. But I found your mail > yesterday to be clearer than the current doc. In the doc you say things like > "the buffer is reordered for display", which is correct but which could also be > misunderstood. The chars are not reordered in the buffer - the buffer itself is > not reordered. It is just that the displayed order differs from the buffer order > (which does not change). I see no "buffer is reordered" in the manual. I see these instead: Reordering of bidirectional text into the "visual" order happens at display time. [...] The buffer-local variable `bidi-display-reordering' controls whether text in the buffer is reordered for display. [...] Because characters are reordered for display, > BTW, maybe the node should be called Bidirectional Text (or Editing > Bidirectional Text) instead of Bidirectional Editing. We've all been doing > bidirectional (multidirectional) editing forever. I will rename the section, thanks.