From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11637 invoked by alias); 14 Jun 2007 17:15:46 -0000 Received: (qmail 11570 invoked by uid 22791); 14 Jun 2007 17:15:45 -0000 X-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00,DK_POLICY_SIGNSOME,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 14 Jun 2007 17:15:37 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.1/8.13.1) with ESMTP id l5EHFXof001682 for ; Thu, 14 Jun 2007 13:15:33 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [10.11.255.20]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l5EHFW9D010399; Thu, 14 Jun 2007 13:15:32 -0400 Received: from [127.0.0.1] (sebastian-int.corp.redhat.com [172.16.52.221]) by pobox.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l5EHFVes023024; Thu, 14 Jun 2007 13:15:31 -0400 Message-ID: <467177C3.3090405@redhat.com> Date: Thu, 14 Jun 2007 17:18:00 -0000 From: Andrew Cagney User-Agent: Thunderbird 1.5.0.12 (X11/20070530) MIME-Version: 1.0 To: Adam Jocksch CC: Stan Cox , Frysk List Subject: Re: hpd command for DisplayValues References: <4671652B.7080206@redhat.com> <1181839209.20944.28.camel@multics.rdu.redhat.com> <46717528.2040700@redhat.com> In-Reply-To: <46717528.2040700@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact frysk-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: frysk-owner@sourceware.org X-SW-Source: 2007-q2/txt/msg00280.txt.bz2 Adam Jocksch wrote: > Hrm, maybe. Although reading in the hpd spec: "By defining > actionpoints, the user may request in advance that target program > execution stop Nice quote, the display object doesn't fit that model since it is passive - it doesn't directly trigger a stop since it doesn't implement a mechanism for detecting changes in the data (that would be watch). Instead it detects when the variable has changed after a stop. For the command line, consider this: > [] break main > [] run .... > main hit > [] print argc > ... > [] step > [] print argc > [] step vs: > [] break main > [] run .... > main hit > [] display argc > ... > [] step > ... value of argc changed from 4 to -1 > [] step > [] step > Value of argc changed from -1 to 4 For a graphical interface the object facilitates the efficient implementation of a variable display window - it will only trigger a redraw of the display elements of the X display when there's something new to draw. Andrew > under certain conditions". Do we want the display to be similar to a > watchpoint, except it applies to an expression rather than a single > variable? Or do we want it to be an expression that is displayed when > the program stops (I remember Andrew saying something about how gdb > does this, and it's bad, so we probably want to avoid that). > > While what the DisplayValue object is capable is well defined, I guess > I'm not 100% sure of how it will be used.