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: How to debug modification to a variable value? Date: Tue, 26 Jan 2010 11:49:38 -0500 Message-ID: References: <87636pvrdj.fsf@thinkpad.tsdh.de> <9131EBDDBDBF4BC384201871CA79A2BE@us.oracle.com> <87d40x5m9b.fsf@thinkpad.tsdh.de> Reply-To: rms@gnu.org NNTP-Posting-Host: lo.gmane.org Content-Type: text/plain; charset=ISO-8859-15 X-Trace: ger.gmane.org 1264525354 24084 80.91.229.12 (26 Jan 2010 17:02:34 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 26 Jan 2010 17:02:34 +0000 (UTC) Cc: drew.adams@oracle.com, emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Jan 26 18:02:27 2010 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 1NZoo6-0001jG-Ew for ged-emacs-devel@m.gmane.org; Tue, 26 Jan 2010 18:02:26 +0100 Original-Received: from localhost ([127.0.0.1]:42055 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NZoo6-0003Vc-Mj for ged-emacs-devel@m.gmane.org; Tue, 26 Jan 2010 12:02:26 -0500 Original-Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NZobn-0006mA-QC for emacs-devel@gnu.org; Tue, 26 Jan 2010 11:49:43 -0500 Original-Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NZobj-0006gS-5b for emacs-devel@gnu.org; Tue, 26 Jan 2010 11:49:43 -0500 Original-Received: from [199.232.76.173] (port=41940 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NZobi-0006gE-Uv for emacs-devel@gnu.org; Tue, 26 Jan 2010 11:49:38 -0500 Original-Received: from fencepost.gnu.org ([140.186.70.10]:55564) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NZobi-00044E-Gp for emacs-devel@gnu.org; Tue, 26 Jan 2010 11:49:38 -0500 Original-Received: from rms by fencepost.gnu.org with local (Exim 4.69) (envelope-from ) id 1NZobi-0002bC-6x; Tue, 26 Jan 2010 11:49:38 -0500 In-reply-to: (message from Stefan Monnier on Tue, 26 Jan 2010 10:17:07 -0500) X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 3) 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:120443 Archived-At: It wouldn't be terribly hard to add one, I think. It would be very bad to use this hook for anything bug debugging, since it means that setting a variable could do anything whatsoever. So if such a featur one is added, it will be very important to make sure it isn't used except for debugging. One way is to design the feature so it always calls the debugger when activated. For instance, if a certain flag is set in a symbol, then setting its value or function slot calls the debugger.