From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 287AAC3A59F for ; Thu, 29 Aug 2019 16:01:16 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 009A920578 for ; Thu, 29 Aug 2019 16:01:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 009A920578 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:51460 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3MrK-0004IZ-B5 for qemu-devel@archiver.kernel.org; Thu, 29 Aug 2019 12:01:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:34065) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3Mpf-0003Y8-OP for qemu-devel@nongnu.org; Thu, 29 Aug 2019 11:59:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i3Mpe-0005iB-LC for qemu-devel@nongnu.org; Thu, 29 Aug 2019 11:59:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48542) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i3Mpb-0005dP-6i; Thu, 29 Aug 2019 11:59:27 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2F66A309B68B; Thu, 29 Aug 2019 15:59:25 +0000 (UTC) Received: from ptitpuce (ovpn-116-165.ams2.redhat.com [10.36.116.165]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1180C60F88; Thu, 29 Aug 2019 15:59:16 +0000 (UTC) References: <20190814100735.24234-1-vsementsov@virtuozzo.com> <20190814100735.24234-3-vsementsov@virtuozzo.com> <3eded188-0161-d494-194c-9d67da644eb1@redhat.com> User-agent: mu4e 1.3.2; emacs 26.2 From: Christophe de Dinechin To: qemu-devel@nongnu.org In-reply-to: <3eded188-0161-d494-194c-9d67da644eb1@redhat.com> Date: Thu, 29 Aug 2019 17:59:13 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.47]); Thu, 29 Aug 2019 15:59:25 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [PATCH 2/2] qapi: deprecate implicit filters X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, libvir-list@redhat.com, armbru@redhat.com, mreitz@redhat.com, abologna@redhat.com, den@openvz.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" John Snow writes: [...] > > This might be OK to do right away, though. > > I asked Markus this not too long ago; do we want to amend the QAPI > schema specification to allow commands to return with "Warning" strings, > or "Deprecated" stings to allow in-band deprecation notices for cases > like these? > > example: > > { "return": {}, > "deprecated": True, > "warning": "Omitting filter-node-name parameter is deprecated, it will > be required in the future" > } > > There's no "error" key, so this should be recognized as success by > compatible clients, but they'll definitely see the extra information. > > Part of my motivation is to facilitate a more aggressive deprecation of > legacy features by ensuring that we are able to rigorously notify users > through any means that they need to adjust their scripts. I like this approach even if there is no consumer today. It does not hurt, and it is indeed a motivation to develop consumers that care. I personally find this much easier to swallow than any kind of crash on deprecation, which already at the BoF seemed like a really big hammer to kill a fly. CC'ing Andrea as well, because we discussed recently about how to deal with error checking in general, and if a new error checking framework is being put in place, adding deprecation to the thinking could be a good idea. -- Cheers, Christophe de Dinechin (IRC c3d)