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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]:53654 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1khwJB-0002Az-P4 for qemu-devel@archiver.kernel.org; Wed, 25 Nov 2020 10:02:13 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:38570) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1khwIG-0001jt-Ri for qemu-devel@nongnu.org; Wed, 25 Nov 2020 10:01:17 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:39859) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1khwID-0001Am-6H for qemu-devel@nongnu.org; Wed, 25 Nov 2020 10:01:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1606316472; 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: in-reply-to:in-reply-to:references:references; bh=AA6tzangRO7wIV4PRgt7mDTHhWmIdo5q5tKwdqjnDLM=; b=SlGP5ORd210D7MODgLqxVvgKS2Q5OpgyPQfho6BRxZMXVX3CODUFpmfjy++Tor9BQ3BKr+ 463OPvQNMuhT+lV1a8RhYOMccTD8mCfAURm9geOqOPJPfy5sgy4gfy8cn6/DF7ha07LGE7 kND0lx6ExstczBxbIsrc05vlFrQIA9A= 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-311-7OZZcjbbMHGER4ekCPxpMA-1; Wed, 25 Nov 2020 10:01:09 -0500 X-MC-Unique: 7OZZcjbbMHGER4ekCPxpMA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A4CF01012E93; Wed, 25 Nov 2020 15:01:08 +0000 (UTC) Received: from localhost (unknown [10.10.67.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6D64B5D6AC; Wed, 25 Nov 2020 15:01:08 +0000 (UTC) Date: Wed, 25 Nov 2020 10:01:07 -0500 From: Eduardo Habkost To: Markus Armbruster Subject: Re: [PATCH v2 3/8] qnum: QNumValue type for QNum value literals Message-ID: <20201125150107.GD2271382@habkost.net> References: <20201119182158.GX1509407@habkost.net> <877dqg8ukz.fsf@dusky.pond.sub.org> <20201120182720.GF2271382@habkost.net> <877dqcwlxc.fsf@dusky.pond.sub.org> <20201123183357.GK2271382@habkost.net> <87ft4zp2at.fsf@dusky.pond.sub.org> <20201124144102.GL2271382@habkost.net> <877dqahjcq.fsf@dusky.pond.sub.org> <20201124152937.GQ2271382@habkost.net> <87y2iqaqhb.fsf@dusky.pond.sub.org> MIME-Version: 1.0 In-Reply-To: <87y2iqaqhb.fsf@dusky.pond.sub.org> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=ehabkost@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=ehabkost@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: Paolo Bonzini , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= , QEMU Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Nov 25, 2020 at 07:40:48AM +0100, Markus Armbruster wrote: > Eduardo Habkost writes: > > > On Tue, Nov 24, 2020 at 04:20:37PM +0100, Markus Armbruster wrote: > >> Eduardo Habkost writes: > >> > >> > On Tue, Nov 24, 2020 at 09:49:30AM +0100, Markus Armbruster wrote: > >> >> Eduardo Habkost writes: > >> >> > >> >> > On Mon, Nov 23, 2020 at 08:51:27AM +0100, Markus Armbruster wrote: > >> >> >> Eduardo Habkost writes: > >> >> >> > >> >> >> > On Fri, Nov 20, 2020 at 06:29:16AM +0100, Markus Armbruster wrote: > >> >> >> [...] > >> >> >> >> When the structure of a data type is to be kept away from its users, I > >> >> >> >> prefer to keep it out of the public header, so the compiler enforces the > >> >> >> >> encapsulation. > >> >> >> > > >> >> >> > I prefer that too, except that it is impossible when users of the > >> >> >> > API need the compiler to know the struct size. > >> >> >> > >> >> >> There are cases where the structure of a data type should be > >> >> >> encapsulated, yet its size must be made known for performance (avoid > >> >> >> dynamic memory allocation and pointer chasing). > >> >> >> > >> >> >> Need for encapsulation correlates with complex algorithms and data > >> >> >> structures. The cost of dynamic allocation is often in the noise then. > >> >> > > >> >> > I don't know what we are talking about anymore. None of this > >> >> > applies to the QNum API, right? > >> >> > > >> >> > QNum/QNumValue are not complex data structures, and the reason we > >> >> > need the compiler to know the size of QNumValue is not related to > >> >> > performance at all. > >> >> > >> >> We started with the question whether to make QNumValue's members > >> >> private. We digressed to the question when to make members private. > >> >> So back to the original question. > >> >> > >> >> > We might still want to discourage users of the QNum API from > >> >> > accessing QNum.u/QNumValue.u directly. Documenting the field as > >> >> > private is a very easy way to do it. > >> >> > >> >> It's a complete non-issue. QNum has been around for years, and we > >> >> haven't had any issues that could've been plausibly avoided by asking > >> >> people to refrain from accessing its members. > >> >> > >> >> If there was an actual need to keep the members private, I'd move the > >> >> struct out of the header, so the compiler enforces privacy. > >> > > >> > Understood. There's still a question I'd like to answer, to > >> > decide how the API documentation should look like: > >> > > >> > Is QNum.u/QNumValue.u required to be part of the API > >> > documentation? > >> > > >> > If accessing that field directly is not necessary for using the > >> > API, I don't think it should appear in the documentation (because > >> > it would be just noise). > >> > >> The current patch's comment on QNumValue looks good to me. > >> > >> Does this answer your question? > > > > The current patch (v3) doesn't address the question. It doesn't > > include documentation for the field, but doesn't hide it. > > kernel-doc will print a warning on that case. > > Do we care? Yes. Peter will reject pull requests if it generates kernel-doc warnings. > How many such warnings exist before the patch? Zero. > Does this series add just this one, or more? The current series (v3) doesn't add any, because I dropped the patch that added QObject and QNum documentation to docs/devel. I still want to resubmit that patch later, though. > > Use your judgement, then be ready to explain it :) OK! -- Eduardo