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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 63F54C432C0 for ; Thu, 21 Nov 2019 15:25:50 +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 2C76B20674 for ; Thu, 21 Nov 2019 15:25:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="IU5Uq+Uy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C76B20674 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]:41854 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXoL7-0006RT-85 for qemu-devel@archiver.kernel.org; Thu, 21 Nov 2019 10:25:49 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:49849) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iXoKD-0005jQ-Fi for qemu-devel@nongnu.org; Thu, 21 Nov 2019 10:24:54 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iXoKC-0006Jq-Bh for qemu-devel@nongnu.org; Thu, 21 Nov 2019 10:24:53 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:20443 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iXoKC-0006JK-8h for qemu-devel@nongnu.org; Thu, 21 Nov 2019 10:24:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1574349891; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vrjEfNCKpbvP2mud/gtTxbxJ6NETRNI2/clN66e647Y=; b=IU5Uq+UyxRUm2bK1lJ50SLcg8XYMx4CgMZvfoRzp5Mw6CWIcUfRq7awRVDPH6KRUAlUdjB uwPCbrm0cDIb3dSkvwid96T3OsZaL4wRObipOg4PFrnGB7ky1lRlQ0Ct0kWDoOsSs9kjxp QC5b4Br/61DiAYNafpOsh9hewd/mVeI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-89-HeDLBC_bOaCDbhegg8PWbQ-1; Thu, 21 Nov 2019 10:24:47 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2B55D8024C0; Thu, 21 Nov 2019 15:24:46 +0000 (UTC) Received: from [10.3.116.221] (ovpn-116-221.phx2.redhat.com [10.3.116.221]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 735AC44FA8; Thu, 21 Nov 2019 15:24:45 +0000 (UTC) Subject: Re: [Qemu-devel] [PATCH v4 03/14] qapi: Introduce default values for struct members To: Markus Armbruster , Max Reitz References: <20190624173935.25747-1-mreitz@redhat.com> <20190624173935.25747-4-mreitz@redhat.com> <87eey1b73y.fsf@dusky.pond.sub.org> From: Eric Blake Organization: Red Hat, Inc. Message-ID: <0214e73e-062e-a9c8-16c9-e99354c07277@redhat.com> Date: Thu, 21 Nov 2019 09:24:44 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <87eey1b73y.fsf@dusky.pond.sub.org> Content-Language: en-US X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-MC-Unique: HeDLBC_bOaCDbhegg8PWbQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=WINDOWS-1252; format=flowed Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.81 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: Kevin Wolf , qemu-devel@nongnu.org, qemu-block@nongnu.org, Michael Roth Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/21/19 9:07 AM, Markus Armbruster wrote: > Max Reitz writes: >=20 >> With this change, it is possible to give default values for struct >> members, as follows: >> >> What you had to do so far: >> >> # @member: Some description, defaults to 42. >> { 'struct': 'Foo', >> 'data': { '*member': 'int' } } >> >> What you can do now: >> >> { 'struct': 'Foo', >> 'data': { '*member': { 'type': 'int', 'default': 42 } } >=20 > The '*' is redundant in this form. >=20 > Can anyone think of reasons for keeping it anyway? Against? Is there ever a reason to allow an optional member but without a=20 'default' value? Or can we just blindly state that if 'default' is not=20 present, that is the same as 'default':0/'default':null? Or, applying your statement further, 'data': { '*a':'int', '*b':'str' } is shorthand for: 'data': { 'a': { 'type':'int', 'default':0 }, 'b': { 'type':'str', 'default':null } } So I could live with permitting '*' only in the shorthand form, and=20 declaring that it is incompatible with longhand form because the=20 existence of a 'default' key in longhand form is evidence that the=20 member is therefore optional. --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org