From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12307 invoked by alias); 14 Jun 2007 17:18:54 -0000 Received: (qmail 12293 invoked by uid 22791); 14 Jun 2007 17:18:53 -0000 X-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00,DK_POLICY_SIGNSOME,FORGED_RCVD_HELO,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 17:18:48 +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 l5EHIjxS003459 for ; Thu, 14 Jun 2007 13:18:45 -0400 Received: from pobox.toronto.redhat.com (pobox.toronto.redhat.com [172.16.14.4]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l5EHIiWs011438; Thu, 14 Jun 2007 13:18:44 -0400 Received: from localhost.localdomain (vpn-14-241.rdu.redhat.com [10.11.14.241]) by pobox.toronto.redhat.com (8.12.11.20060308/8.12.11) with ESMTP id l5EHIhla029186; Thu, 14 Jun 2007 13:18:43 -0400 Message-ID: <46717870.4080805@redhat.com> Date: Thu, 14 Jun 2007 17:34:00 -0000 From: Adam Jocksch User-Agent: Thunderbird 2.0.0.0 (X11/20070419) MIME-Version: 1.0 To: Andrew Cagney 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> <467177C3.3090405@redhat.com> In-Reply-To: <467177C3.3090405@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/msg00281.txt.bz2 Andrew Cagney wrote: > 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. > That sounds similar to what I had envisioned.