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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 8992EC3A5A9 for ; Mon, 4 May 2020 13:29:27 +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 527FA2075B for ; Mon, 4 May 2020 13:29:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fHRqMwmL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 527FA2075B 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]:42866 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jVb9y-0008RF-G9 for qemu-devel@archiver.kernel.org; Mon, 04 May 2020 09:29:26 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:36776) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jVb9M-0007uW-IX for qemu-devel@nongnu.org; Mon, 04 May 2020 09:28:48 -0400 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:40073 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jVb9L-0003Ho-RZ for qemu-devel@nongnu.org; Mon, 04 May 2020 09:28:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588598926; 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=ArTO3f15g9+tIA1vP96wRxM6KoaDCT/8Is1f4TZJIDU=; b=fHRqMwmLeeaLJ2wayFmDAttI3VNQ+a7u4+fMajkl6JZnhDxsqbDO19jfHlpPqdOQOonTWN Ojou2M2MYLBFM6tLYHYAUgIlh6pKnZEHzx+9Peyc2c2yKIzdBlHlnWtKJdI5R8srIf6b6s 4u9K+mufNNK2WSyHfMlf6azx8eda5Lg= 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-125-8GDAo5-sMOCRMbsdjY8DDQ-1; Mon, 04 May 2020 09:28:43 -0400 X-MC-Unique: 8GDAo5-sMOCRMbsdjY8DDQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 45CDA107ACF3; Mon, 4 May 2020 13:28:42 +0000 (UTC) Received: from [10.3.114.73] (ovpn-114-73.phx2.redhat.com [10.3.114.73]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E06165C1B2; Mon, 4 May 2020 13:28:41 +0000 (UTC) Subject: Re: [PATCH v2 3/6] qemu-img: Add bitmap sub-command To: Max Reitz , qemu-devel@nongnu.org References: <20200421212019.170707-1-eblake@redhat.com> <20200421212019.170707-4-eblake@redhat.com> <1dcf85b6-d9e6-b952-537c-791daec34ad9@redhat.com> <9d4769d4-09ea-dced-d4bd-9ceb33044202@redhat.com> From: Eric Blake Organization: Red Hat, Inc. Message-ID: Date: Mon, 4 May 2020 08:28:40 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=207.211.31.81; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/04 08:14:53 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action 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, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 5/4/20 5:01 AM, Max Reitz wrote: >>>> +.. option:: bitmap {--add [-g GRANULARITY] [--disabled] | --remove | >>>> --clear | --enable | --disable | --merge SOURCE_BITMAP [-b >>>> SOURCE_FILE [-F SOURCE_FMT]]} [--object OBJECTDEF] [--image-opts] [-f >>>> FMT] FILENAME BITMAP >>> >>> So I can do multiple operations in one roll, but they all use the same >>> BITMAP?=C2=A0 Sounds a bit weird.=C2=A0 It actually took me a while to = understands >>> this, because I thought for sure that each command would take a bitmap >>> name.=C2=A0 (And was ready to complain that it looked like they don=E2= =80=99t, but, >>> well, that=E2=80=99s because they don=E2=80=99t.) >> >> All of the operations take one bitmap name (the final BITMAP). >> Additionally, the --merge operation takes a second bitmap name >> (SOURCE_BITMAP).=C2=A0 None of the other operations need a second bitmap >> name, so only --merge requires an option argument.=C2=A0 As written, the= { a >> | b | c } implies that operations are mutually exclusive: you can only >> request one operation per qemu-img invocation. >=20 > Well, as I found out later it=E2=80=99s supposed to imply that. I always= expect > {} to mean repetition. >> In command line syntax, I'm most used to seeing repetition as '...', >> optional as [], and mutually-exclusive choice as {|}.=C2=A0 Yes, that's >> different than EBNF. >=20 > It=E2=80=99s confusing is what it is, and unnecessarily so. The | alread= y > signifies exclusion: Say there are -a and -b, if they=E2=80=99re not mutu= ally > exclusive, then the doc describe them as =E2=80=9C[-a] [-b]=E2=80=9D; if = they are, it=E2=80=99d > be =E2=80=9C-a | -b=E2=80=9D. Maybe =E2=80=9C(-a | -b)=E2=80=9D. Is s/{/(/ is all the more that would be needed to take this patch as-is?=20 Or should I really try and re-write it to take a list of operations,=20 and iterate through the list until the first failure? (At any rate, I'll probably end up trying that anyways, just for=20 comparison in the lines of code...) --=20 Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3226 Virtualization: qemu.org | libvirt.org