From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:43555) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S9ic8-0000Cn-Pv for qemu-devel@nongnu.org; Mon, 19 Mar 2012 15:51:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S9ic4-0006vD-4A for qemu-devel@nongnu.org; Mon, 19 Mar 2012 15:51:32 -0400 Received: from mail-wg0-f53.google.com ([74.125.82.53]:62767) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S9ic3-0006v1-SC for qemu-devel@nongnu.org; Mon, 19 Mar 2012 15:51:28 -0400 Received: by wgbfm10 with SMTP id fm10so1008371wgb.10 for ; Mon, 19 Mar 2012 12:51:25 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <4F678E38.7050902@redhat.com> Date: Mon, 19 Mar 2012 20:51:20 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1332185368-18708-1-git-send-email-pbonzini@redhat.com> <4F678A37.1020101@codemonkey.ws> In-Reply-To: <4F678A37.1020101@codemonkey.ws> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC/RFA PATCH] qapi: detect extra members inside structs List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Michael Roth , qemu-devel@nongnu.org, lcapitulino@redhat.com Il 19/03/2012 20:34, Anthony Liguori ha scritto: >> >> Is this acceptable or just wrong? > > This is a feature. The idea is that with QMP, old clients just ignore > extra members in a structure. I've never felt that comfortable with > this as a semantic but this is how QMP was designed. For old clients that could be fine. But what about old servers? :) Perhaps we need an argument to the QMPInputVisitor constructor to control this. > If you don't allow this semantic, then it's impossible to ever add a > field to an existing type as that would break backwards compatibility. Paolo