From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Marcin Borkowski Newsgroups: gmane.emacs.bugs Subject: bug#20663: page.el (forward-page): Avoid skipping pages Date: Sat, 16 Apr 2016 13:03:41 +0200 Message-ID: <8760vhvmr9.fsf@mbork.pl> References: <20150526171440.GG647@gmail.com> <87h9fbum2w.fsf@mbork.pl> <83h9fbhu0p.fsf@gnu.org> <871t6eve9c.fsf@mbork.pl> <837fg6injl.fsf@gnu.org> <20160410012924.GA23097@gmail.com> <87fuus30rs.fsf@mbork.pl> <8337qsgnvc.fsf@gnu.org> <87a8kxcs4k.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1460804670 21951 80.91.229.3 (16 Apr 2016 11:04:30 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 16 Apr 2016 11:04:30 +0000 (UTC) Cc: 20663@debbugs.gnu.org, ambrevar@gmail.com To: Eli Zaretskii Original-X-From: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Sat Apr 16 13:04:15 2016 Return-path: Envelope-to: geb-bug-gnu-emacs@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 1arO1M-0007GL-Dt for geb-bug-gnu-emacs@m.gmane.org; Sat, 16 Apr 2016 13:04:12 +0200 Original-Received: from localhost ([::1]:53401 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1arO1L-0007Ds-S8 for geb-bug-gnu-emacs@m.gmane.org; Sat, 16 Apr 2016 07:04:11 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:54779) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1arO1G-000785-7s for bug-gnu-emacs@gnu.org; Sat, 16 Apr 2016 07:04:07 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1arO1C-0004Ug-S8 for bug-gnu-emacs@gnu.org; Sat, 16 Apr 2016 07:04:06 -0400 Original-Received: from debbugs.gnu.org ([208.118.235.43]:52991) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1arO1C-0004Uc-PJ for bug-gnu-emacs@gnu.org; Sat, 16 Apr 2016 07:04:02 -0400 Original-Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1arO1C-0006y6-H0 for bug-gnu-emacs@gnu.org; Sat, 16 Apr 2016 07:04:02 -0400 X-Loop: help-debbugs@gnu.org Resent-From: Marcin Borkowski Original-Sender: "Debbugs-submit" Resent-CC: bug-gnu-emacs@gnu.org Resent-Date: Sat, 16 Apr 2016 11:04:02 +0000 Resent-Message-ID: Resent-Sender: help-debbugs@gnu.org X-GNU-PR-Message: followup 20663 X-GNU-PR-Package: emacs X-GNU-PR-Keywords: Original-Received: via spool by 20663-submit@debbugs.gnu.org id=B20663.146080463126767 (code B ref 20663); Sat, 16 Apr 2016 11:04:02 +0000 Original-Received: (at 20663) by debbugs.gnu.org; 16 Apr 2016 11:03:51 +0000 Original-Received: from localhost ([127.0.0.1]:37095 helo=debbugs.gnu.org) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1arO11-0006xf-7e for submit@debbugs.gnu.org; Sat, 16 Apr 2016 07:03:51 -0400 Original-Received: from mail.mojserwer.eu ([195.110.48.8]:47690) by debbugs.gnu.org with esmtp (Exim 4.84_2) (envelope-from ) id 1arO0z-0006xX-RX for 20663@debbugs.gnu.org; Sat, 16 Apr 2016 07:03:50 -0400 Original-Received: from localhost (localhost [127.0.0.1]) by mail.mojserwer.eu (Postfix) with ESMTP id CE786ACB507; Sat, 16 Apr 2016 13:03:47 +0200 (CEST) X-Virus-Scanned: Debian amavisd-new at mail.mojserwer.eu Original-Received: from mail.mojserwer.eu ([127.0.0.1]) by localhost (mail.mojserwer.eu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id OzPnMrLhwb63; Sat, 16 Apr 2016 13:03:45 +0200 (CEST) Original-Received: from localhost (98-171.echostar.pl [213.156.98.171]) by mail.mojserwer.eu (Postfix) with ESMTPSA id 153E8ACB506; Sat, 16 Apr 2016 13:03:45 +0200 (CEST) User-agent: mu4e 0.9.13; emacs 25.1.50.8 In-reply-to: <87a8kxcs4k.fsf@mbork.pl> X-BeenThere: debbugs-submit@debbugs.gnu.org X-Mailman-Version: 2.1.18 Precedence: list X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 208.118.235.43 X-BeenThere: bug-gnu-emacs@gnu.org List-Id: "Bug reports for GNU Emacs, the Swiss army knife of text editors" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-gnu-emacs-bounces+geb-bug-gnu-emacs=m.gmane.org@gnu.org Original-Sender: "bug-gnu-emacs" Xref: news.gmane.org gmane.emacs.bugs:116521 Archived-At: On 2016-04-13, at 17:53, Marcin Borkowski wrote: > Here's the relevant excerpt from the manual: > > --8<---------------cut here---------------start------------->8--- > The variable ‘page-delimiter’ controls where pages begin. Its value > is a regular expression that matches the beginning of a line that > separates pages (*note Regexps::). The normal value of this variable is > ‘"^\f"’, which matches a formfeed character at the beginning of a line. > --8<---------------cut here---------------end--------------->8--- > > Is it me or is the above ambiguous? > > > I'm a bit busy now, but I'll make a second attempt at this issue within > a few days. One of the problems is that (as the above paragraph seems > to confirm) the very notion of a "page" in Emacs is vague. IMHO we > should start with a clear definition of a "page". It is well possible > that different functions in page.el use different interpretations of > this notion, and the bug is just a symptom if such a mess. > > My proposal is that a "page separator" would be a position in the buffer > where (looking-at-p page-delimiter) is true, and if point is at such > a place, then we consider it on the next page. I.e., in this situation > > abcabcabc > -!-^L > cbacbacba > > the point is already on the second page (unlike the default Emacs > behavior). > > Then, someone should study page.el and where necessary, update it to the > precisely defined notion of a "page". (The mythical "someone" might be > me.) > > WDYT? OK, I got almost no responses so far:-(. In the meantime, I started to study this issue. It seems that `forward-page' indeed has a bug. Here's the recipe (slightly modified from the OP's one). With this buffer state: --8<---------------cut here---------------start------------->8--- Page 1 -!-^L Page 2 ^L Page 3 --8<---------------cut here---------------end--------------->8--- press `C-x ]' (`forward-page'). Now the point moves across /two/ form-feed characters. Is that intentional? Seems broken for me. Best, -- Marcin Borkowski http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski Faculty of Mathematics and Computer Science Adam Mickiewicz University