From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Richard Stallman Newsgroups: gmane.emacs.devel Subject: Re: [rant] Should reverting a buffer really discard undo history? Date: Tue, 31 May 2005 13:47:59 -0400 Message-ID: References: <87ll5w5vxa.fsf@wigwam.deepwood.net> Reply-To: rms@gnu.org NNTP-Posting-Host: main.gmane.org X-Trace: sea.gmane.org 1117561761 2224 80.91.229.2 (31 May 2005 17:49:21 GMT) X-Complaints-To: usenet@sea.gmane.org NNTP-Posting-Date: Tue, 31 May 2005 17:49:21 +0000 (UTC) Cc: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue May 31 19:49:19 2005 Return-path: Original-Received: from lists.gnu.org ([199.232.76.165]) by ciao.gmane.org with esmtp (Exim 4.43) id 1DdAqK-0000b0-0q for ged-emacs-devel@m.gmane.org; Tue, 31 May 2005 19:47:56 +0200 Original-Received: from localhost ([127.0.0.1] helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DdAvR-00044x-TU for ged-emacs-devel@m.gmane.org; Tue, 31 May 2005 13:53:13 -0400 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1DdAtl-0003Dj-QN for emacs-devel@gnu.org; Tue, 31 May 2005 13:51:29 -0400 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1DdAtj-0003CY-U2 for emacs-devel@gnu.org; Tue, 31 May 2005 13:51:28 -0400 Original-Received: from [199.232.76.173] (helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1DdAtj-0003CD-Lw for emacs-devel@gnu.org; Tue, 31 May 2005 13:51:27 -0400 Original-Received: from [199.232.76.164] (helo=fencepost.gnu.org) by monty-python.gnu.org with esmtp (Exim 4.34) id 1DdAt1-0006PI-Ob for emacs-devel@gnu.org; Tue, 31 May 2005 13:50:43 -0400 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.34) id 1DdAqN-0001LP-AB; Tue, 31 May 2005 13:47:59 -0400 Original-To: Daniel Brockman In-reply-to: <87ll5w5vxa.fsf@wigwam.deepwood.net> (message from Daniel Brockman on Mon, 30 May 2005 21:57:21 +0200) 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:37950 X-Report-Spam: http://spam.gmane.org/gmane.emacs.devel:37950 1. C-x C-f foo RET original contents C-x C-s 2. M-! echo new contents > foo RET 3. Try to change the buffer. 4. Answer `r' to the question about really editing the buffer. 5. Note that at this point you cannot retrieve the original buffer contents by undoing. In theory, we could treat the revert operation as an undoable change to the buffer contents. In practice, for large buffers, that change would be so large that it would soon be discarded from the undo list. For even larger buffers, the result of saving the whole buffer as an undo record would be an immediate error. It would be impossible to revert. So I am against this change--at least if it were the default.