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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 499B2C6FA82 for ; Thu, 22 Sep 2022 10:54:47 +0000 (UTC) Received: from localhost ([::1]:36396 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1obJqw-00040h-1K for qemu-devel@archiver.kernel.org; Thu, 22 Sep 2022 06:54:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42098) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obIfS-0003CQ-VS for qemu-devel@nongnu.org; Thu, 22 Sep 2022 05:38:59 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:37929) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obIfP-0001qC-Sv for qemu-devel@nongnu.org; Thu, 22 Sep 2022 05:38:50 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663839527; 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=7HDkriJMU+yRv8tQrJJXlmmc4JN3lh26uYZ10S4+ccc=; b=RzueRZdJ+G46Qd7US0zIU8/wSBU6R0vijhsq9A7V3h9b5dxPacwn370BTH4qTeOrFSc8pf VoqRwikxxUcRAczp0eGr6x88Wp2lEFnCDJx46nzousaCF9eysbQWNiEeNY70+7ZmUIqSAQ LGOACWE011P+wYIpEeIucMbb49Cmkf4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-524-42eclFc4PRScPY78xqhXNA-1; Thu, 22 Sep 2022 05:38:44 -0400 X-MC-Unique: 42eclFc4PRScPY78xqhXNA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 92492294EDEE; Thu, 22 Sep 2022 09:38:44 +0000 (UTC) Received: from blackfin.pond.sub.org (unknown [10.39.192.163]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4EF442166B5E; Thu, 22 Sep 2022 09:38:44 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id B5D1721E6900; Thu, 22 Sep 2022 11:38:42 +0200 (CEST) From: Markus Armbruster To: Daniel P. =?utf-8?Q?Berrang=C3=A9?= Cc: Claudio Fontana , Philippe =?utf-8?Q?Mathieu-Daud?= =?utf-8?Q?=C3=A9?= , Paolo Bonzini , Richard Henderson , Kevin Wolf , qemu-devel@nongnu.org, dinechin@redhat.com, Gerd Hoffmann , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau Subject: Re: [PATCH v4 2/3] module: add Error arguments to module_load_one and module_load_qom_one References: <20220908183012.17667-1-cfontana@suse.de> <20220908183012.17667-3-cfontana@suse.de> <877d23ekj0.fsf@pond.sub.org> <76775f64-e49a-1c3c-0d73-10d93eff34e4@amsat.org> <87y1ucdirx.fsf@pond.sub.org> <878rmc54cw.fsf@pond.sub.org> Date: Thu, 22 Sep 2022 11:38:42 +0200 In-Reply-To: ("Daniel P. =?utf-8?Q?Berrang?= =?utf-8?Q?=C3=A9=22's?= message of "Thu, 22 Sep 2022 09:28:35 +0100") Message-ID: <87leqb4ul9.fsf@pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Received-SPF: pass client-ip=170.10.133.124; envelope-from=armbru@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 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_LOW=-0.7, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Daniel P. Berrang=C3=A9 writes: > On Thu, Sep 22, 2022 at 08:07:43AM +0200, Markus Armbruster wrote: >> Ease of use matters, too. When sticking to the rule leads to awkward >> code, we should stop and think. Should we deviate from the rule? Or >> can we avoid that by tweaking the interface? >>=20 >> Philippe's proposed interface sticks to the rule. > > The cost is that when you see a function dosomething(true|false) as > a reader you often have no idea what the effect of true vs false is > on the behaviour of that function. You resort to looking at the > API docs and/or code. This is where C would really benefit from > having named parameters like as dosomething(ignore_errors=3Dtrue|false) > is totally obvious. Anyway, I digress. Right. Quoting myself: "If having to pass a flag turns out to to be a legibility issue, we can have wrapper functions." :) >> Another interface that does: return -1 for error, 0 for module not found >> (no error), and 1 for loaded. > > IMHO this pattern is generally easier to understand when looking at > the callers, as the fatal error scenario is always clear. > > That said I would suggest neither approach as the public facing > API. Rather stop trying to overload 3 states onto an error reporting > pattern that inherantly wants to be 2 states. Instead just have > distinct methods Like these: > bool module_load_one(const char *prefix, const char *name, Error *errp) > bool module_try_load_one(const char *prefix, const char *name, Error *e= rrp) > > other names are available for the second, eg module_load_one_optional() module_load_one_if_there()? By the way, the "one" in "module_load_one" & friends feels redundant. When I see "module_load", I assume it loads one module. > Internally, both would call into a common helper following either > Philippe's idea, or the -1/0/1 int return value. Either is fine, > as they won't be exposed to any caller. Yup.