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 D8257C6FA82 for ; Thu, 22 Sep 2022 08:35:22 +0000 (UTC) Received: from localhost ([::1]:34190 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1obHg1-0005eB-L8 for qemu-devel@archiver.kernel.org; Thu, 22 Sep 2022 04:35:21 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60522) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obHaA-0004DB-Cj for qemu-devel@nongnu.org; Thu, 22 Sep 2022 04:29:18 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:31646) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1obHa7-00017p-7D for qemu-devel@nongnu.org; Thu, 22 Sep 2022 04:29:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1663835354; h=from:from:reply-to: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=3LeZHcA1Wf8BabMFgBBHCZjKCQ5rsWin9KAVQKz6iSA=; b=DUbT5pmtZx97dTlW1NdWEGyKMCaJNM8Ju2eeE936x3UMhhOh3gGHNe9fcQ+PXbaqN3+XML 1k/jK67IUyjnpDaWpqEnVz5zab5J1YHdidB4WozIL10jySuBRrWeodca+b5JRXdp0T5eMl dLa3Ag/t7BwZroUsHhbZdo+6+vkL1Fc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-642-Ikgy_yFqPiym8aCgXH8MOA-1; Thu, 22 Sep 2022 04:29:10 -0400 X-MC-Unique: Ikgy_yFqPiym8aCgXH8MOA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 6E1E78828C3; Thu, 22 Sep 2022 08:29:10 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.120]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9AC4C53AA; Thu, 22 Sep 2022 08:28:38 +0000 (UTC) Date: Thu, 22 Sep 2022 09:28:35 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: Claudio Fontana , Philippe =?utf-8?Q?Mathieu-Daud=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 Message-ID: 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <878rmc54cw.fsf@pond.sub.org> User-Agent: Mutt/2.2.6 (2022-06-05) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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? > > 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=true|false) is totally obvious. Anyway, I digress. > 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 bool module_load_one(const char *prefix, const char *name, Error *errp) bool module_try_load_one(const char *prefix, const char *name, Error *errp) other names are available for the second, eg module_load_one_optional() 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. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|