From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Removing rollback from VC mode - request for comment Date: Thu, 11 Dec 2014 14:40:49 -0500 Message-ID: References: <20141211092138.6D5F6C008E@snark.thyrsus.com> <20141211183649.GE581@thyrsus.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1418327968 27136 80.91.229.3 (11 Dec 2014 19:59:28 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 11 Dec 2014 19:59:28 +0000 (UTC) Cc: "Eric S. Raymond" , emacs-devel@gnu.org To: "Eric S. Raymond" Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Thu Dec 11 20:59:21 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 1Xz9tP-00010U-EB for ged-emacs-devel@m.gmane.org; Thu, 11 Dec 2014 20:59:19 +0100 Original-Received: from localhost ([::1]:54138 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xz9tP-0006QQ-4G for ged-emacs-devel@m.gmane.org; Thu, 11 Dec 2014 14:59:19 -0500 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:37767) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xz9tE-0006QJ-7M for emacs-devel@gnu.org; Thu, 11 Dec 2014 14:59:15 -0500 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Xz9t6-0004Gg-9P for emacs-devel@gnu.org; Thu, 11 Dec 2014 14:59:08 -0500 Original-Received: from ironport2-out.teksavvy.com ([206.248.154.181]:1780) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Xz9t6-0004GS-4L for emacs-devel@gnu.org; Thu, 11 Dec 2014 14:59:00 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AjsPAOwQflRFxIGR/2dsb2JhbABbgweDYIVaxR0EAgKBJBcBAQEBAQF8hAMBAQMBViMFCws0EhQYDSSISgnWWQEBAQEGAQEBAR6QbweESAWLAZIxgziORYF4hBkhgncBAQE X-IPAS-Result: AjsPAOwQflRFxIGR/2dsb2JhbABbgweDYIVaxR0EAgKBJBcBAQEBAQF8hAMBAQMBViMFCws0EhQYDSSISgnWWQEBAQEGAQEBAR6QbweESAWLAZIxgziORYF4hBkhgncBAQE X-IronPort-AV: E=Sophos;i="5.07,502,1413259200"; d="scan'208";a="100220789" Original-Received: from 69-196-129-145.dsl.teksavvy.com (HELO pastel.home) ([69.196.129.145]) by ironport2-out.teksavvy.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 11 Dec 2014 14:58:58 -0500 Original-Received: by pastel.home (Postfix, from userid 20848) id 721DF12FD; Thu, 11 Dec 2014 14:40:49 -0500 (EST) In-Reply-To: <20141211183649.GE581@thyrsus.com> (Eric S. Raymond's message of "Thu, 11 Dec 2014 13:36:49 -0500") User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 206.248.154.181 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:179830 Archived-At: >> Actually, I think most VCS can support it one way or another. > It's not hard to simulate using what in git terms is a reverse cherry pick. IIUC "reverse cherry pick" adds a new commit, so it's a different operation, which does not require any special support (it's a normal cherry pick, basically). > But modifying history in place is very difficult to do with a good outcome. The "clean" way to look at this feature is: - create a new branch BAR off of the target revision. - delete the current branch FOO. - rename BAR to FOO. - adjust the current checkout, if needed, in accordance with the new FOO. AFAIK, most current VCS offer those operations. > It'll take a while, though. Michael Albinus and I are finding a lot > of bit-rot. He just told me that six of the eight working-revision > backend functions don't work right. Much repair is required before > adding new features. That's OK, but: - please make sure you get back promptly to replacing the removed features. - the more important the feature, the shorter the delay before you replace it. Stefan