From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.devel Subject: Re: using empty_string as the only "" string Date: Fri, 27 Apr 2007 12:29:11 +0200 Message-ID: <85odlaglfs.fsf@lola.goethe.zz> References: <462EE947.000007.15251@camay.yandex.ru> <4630A339.7000005@yandex.ru> <4631CA91.9020806@yandex.ru> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: sea.gmane.org 1177670029 4534 80.91.229.12 (27 Apr 2007 10:33:49 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Fri, 27 Apr 2007 10:33:49 +0000 (UTC) Cc: , emacs-devel@gnu.org To: Dmitry Antipov Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Apr 27 12:33:47 2007 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 4.50) id 1HhNln-0007NX-Mu for ged-emacs-devel@m.gmane.org; Fri, 27 Apr 2007 12:33:44 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1HhNrc-0002aP-M1 for ged-emacs-devel@m.gmane.org; Fri, 27 Apr 2007 06:39:44 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1HhNnJ-0004Qv-K9 for emacs-devel@gnu.org; Fri, 27 Apr 2007 06:35:17 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1HhNnI-0004Pn-SR for emacs-devel@gnu.org; Fri, 27 Apr 2007 06:35:17 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1HhNnI-0004PS-Nj for emacs-devel@gnu.org; Fri, 27 Apr 2007 06:35:16 -0400 Original-Received: from fencepost.gnu.org ([199.232.76.164]) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1HhNhS-0001Pe-1O for emacs-devel@gnu.org; Fri, 27 Apr 2007 06:29:14 -0400 Original-Received: from [127.0.0.1] (helo=lola.goethe.zz) by fencepost.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1HhNem-000305-De; Fri, 27 Apr 2007 06:26:28 -0400 Original-Received: by lola.goethe.zz (Postfix, from userid 1002) id 756411C13429; Fri, 27 Apr 2007 12:29:11 +0200 (CEST) In-Reply-To: <4631CA91.9020806@yandex.ru> (Dmitry Antipov's message of "Fri\, 27 Apr 2007 14\:04\:01 +0400") User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.98 (gnu/linux) X-detected-kernel: Linux 2.6, seldom 2.4 (older, 4) 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:70236 Archived-At: Dmitry Antipov writes: > Richard Stallman wrote: >> Also note that canonicalization of null strings assumes that >> non-null interval can't be attached to empty string regardless of >> it's multibyteness (at a first glance, this is how the stuff ticks >> now, but I'm not sure about this). >> >> Alas, I don't understand those words. > > Is it possible that STRING_INTERVALS(s) is not NULL if 's' is an empty string, > unibyte or multibyte ? I believe no (at least, 'set-text-properties' can't > attach properties to empty string). > > Otherwise it would be nearly impossible to canonicalize empty > strings since each empty string may have unique intervals. Buffers have overlays (and text), strings merely have text and that text can have text properties on characters. If an empty string contains either, it would appear to be a bug. Things are different in XEmacs, where both are represented by "extents" which can be empty in strings, too. -- David Kastrup, Kriemhildstr. 15, 44793 Bochum