From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Eric S. Raymond" Newsgroups: gmane.emacs.devel Subject: Re: resolving ambiguity in action stamps (was: Everyone, please stop making my life more difficult) Date: Fri, 12 Sep 2014 16:41:12 -0400 Organization: Eric Conspiracy Secret Labs Message-ID: <20140912204111.GA12328@thyrsus.com> References: <20140912043652.4D6D8380604@snark.thyrsus.com> <83zje56ymd.fsf@gnu.org> <20140912083430.GA32586@thyrsus.com> <87mwa59i1r.fsf@igel.home> <20140912115739.GA3403@thyrsus.com> <87d2b19cbr.fsf@igel.home> <20140912155410.GA5086@thyrsus.com> <877g188uc3.fsf_-_@slice.rozzin.com> Reply-To: esr@thyrsus.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1410554534 2705 80.91.229.3 (12 Sep 2014 20:42:14 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 12 Sep 2014 20:42:14 +0000 (UTC) Cc: Eli Zaretskii , Andreas Schwab , emacs-devel@gnu.org To: Joshua Judson Rosen Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Sep 12 22:42:09 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 1XSXfT-00022N-Ne for ged-emacs-devel@m.gmane.org; Fri, 12 Sep 2014 22:42:07 +0200 Original-Received: from localhost ([::1]:47301 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XSXfT-0003QX-7F for ged-emacs-devel@m.gmane.org; Fri, 12 Sep 2014 16:42:07 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37536) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XSXfD-0003QN-Oa for emacs-devel@gnu.org; Fri, 12 Sep 2014 16:41:55 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XSXf9-00051E-JB for emacs-devel@gnu.org; Fri, 12 Sep 2014 16:41:51 -0400 Original-Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5]:36876 helo=snark.thyrsus.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XSXf5-00050K-49; Fri, 12 Sep 2014 16:41:43 -0400 Original-Received: by snark.thyrsus.com (Postfix, from userid 1000) id 467D338066F; Fri, 12 Sep 2014 16:41:12 -0400 (EDT) Content-Disposition: inline In-Reply-To: <877g188uc3.fsf_-_@slice.rozzin.com> X-Eric-Conspiracy: There is no conspiracy User-Agent: Mutt/1.5.21 (2010-09-15) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 71.162.243.5 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:174257 Archived-At: Joshua Judson Rosen : > Sorry--I mostly just wasn't paying close enough attention six months ago > to point out all of the angles of this issue...; though I *did* raise > this "ambiguity of reference by timestamp" issue at that time--and thought > that you'd given an ACK with a statement you were going to fix it by using > "#{sequence-number}" suffixes to distingiush between multiple distinct > items in the same "{ISO-date}!{email-address}" hashbucket: > > https://lists.gnu.org/archive/html/emacs-devel/2014-01/msg01117.html > > https://lists.gnu.org/archive/html/emacs-devel/2014-01/msg01113.html > > (that first link is your response; the second is my message--which > included an example of why the "same timestamps, different commit- > objects" situation might exist in a repository) I remeber that. I thought I was going to fix it that way too. Then I found a showstopper. Possibly it has a solution I haven't found yet. The problem is this: suppose you have such a suffix, and several nodes with the same date on a DAG. What's your rule for mapping suffix to individual node? I couldn't invent one. I believe this is mathematically equivalent to total-ordering the DAG. Which you can't do. -- Eric S. Raymond