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: Repo cpnversion progress report Date: Fri, 31 Jan 2014 16:07:18 -0500 Organization: Eric Conspiracy Secret Labs Message-ID: <20140131210718.GA19192@thyrsus.com> References: <20140130195557.GA8405@thyrsus.com> <83iot16u66.fsf@gnu.org> <20140130214201.GA9204@thyrsus.com> <83ha8k7fp0.fsf@gnu.org> <87iot0f481.fsf@ktab.red-bean.com> <20140131181612.GA18170@thyrsus.com> <52EBFD17.1050006@cs.ucla.edu> 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 1391202442 30778 80.91.229.3 (31 Jan 2014 21:07:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 31 Jan 2014 21:07:22 +0000 (UTC) Cc: emacs-devel@gnu.org To: Paul Eggert Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Jan 31 22:07:31 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 1W9LJC-0002Ja-8w for ged-emacs-devel@m.gmane.org; Fri, 31 Jan 2014 22:07:30 +0100 Original-Received: from localhost ([::1]:58009 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W9LJB-0006O6-QV for ged-emacs-devel@m.gmane.org; Fri, 31 Jan 2014 16:07:29 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:45916) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W9LJ5-0006NB-Mu for emacs-devel@gnu.org; Fri, 31 Jan 2014 16:07:27 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W9LJ1-0008GO-Nr for emacs-devel@gnu.org; Fri, 31 Jan 2014 16:07:23 -0500 Original-Received: from static-71-162-243-5.phlapa.fios.verizon.net ([71.162.243.5]:37485 helo=snark.thyrsus.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W9LJ1-0008GI-JC for emacs-devel@gnu.org; Fri, 31 Jan 2014 16:07:19 -0500 Original-Received: by snark.thyrsus.com (Postfix, from userid 1000) id BD120380695; Fri, 31 Jan 2014 16:07:18 -0500 (EST) Content-Disposition: inline In-Reply-To: <52EBFD17.1050006@cs.ucla.edu> 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:169297 Archived-At: Paul Eggert : > Eric S. Raymond wrote: > >I hear the argument about forensics, but the Bazaar revision numbers > >are no more helpful for that than the action stamps. > > As someone who regularly spelunks back decades, I'd prefer keeping > these stamps as small as possible. Even > "2003-07-05T12:41:24!Roland.Winkler@physik.uni-erlangen.de" will > cause hassles, and I especially wouldn't want to read and digest > monsters along the lines of what someone else proposed, e.g., > "1985-04-18T00:49:29!jimb@redhat.com (bzr 1) (CVS 4.35.2.1) (RCS > 1.71) (emacs-backup ~107~)". It doesn't scale for a revision string > to contain all the names that the revision has ever had, for all the > version-control systems we've ever used. Yeah, exactly. That's the telling argument for a single VCS-independent action stamp, right there. And props to you for taking the (correctly) long view of the matter! I'm not real happy about the action stamps being so long as it is. Unfortunately, they're the shortest thing I've managed to come up with that has the required properties of being unique and self-describing. > PS. In that 1985 example, the email address jimb@redhat.com is > ahistorical, as Red Hat didn't exist in 1985. That info is taken > straight from the current bzr repository. Most likely the > repository was made ahistorical during an earlier conversion, > unfortunately. Yes, and that sort of ahistoricity was unavoidable for the simple reason that DVCSes need email addresses as Internet-global credentials. The act of mapping CVS usernames to these therefore almost necessarily introduces anachronisms. Repository translation is *difficult*. At least, doing a non-half-assed job of it is. The tradeoffs between usability and historicity don't have easy or pat answers. It's especially difficult for a project as steeped in history - nay, positively encrusted with it - as Emacs. This is already the hairiest conversion I've ever done, measured by complexity of the lift file, and it's going to get much worse before it's done. I don't expect to ever see a messier one. -- Eric S. Raymond