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Thu, 2 Apr 2020 08:49:05 +0000 (UTC) Received: from redhat.com (unknown [10.36.110.55]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 337ED5D9CA; Thu, 2 Apr 2020 08:49:03 +0000 (UTC) Date: Thu, 2 Apr 2020 09:49:00 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Maydell Subject: Re: Questionable aspects of QEMU Error's design Message-ID: <20200402084900.GC423991@redhat.com> References: <87o8sblgto.fsf@dusky.pond.sub.org> <87sghmbfgc.fsf@dusky.pond.sub.org> <44b5ff2c-6dce-e516-a9cc-9d80354c5a72@virtuozzo.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.13.3 (2020-01-12) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline 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: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Vladimir Sementsov-Ogievskiy , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , Markus Armbruster , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Apr 02, 2020 at 08:11:11AM +0000, Peter Maydell wrote: > On Thu, 2 Apr 2020 at 07:11, Vladimir Sementsov-Ogievskiy > wrote: > > Somehow, in general, especially with long function names and long param= eter lists I prefer > > > > ret =3D func(..); > > if (ret < 0) { > > return ret; > > } >=20 > Personally I prefer the other approach -- this one has an extra line > in the source and > needs an extra local variable. >=20 > > Are you sure that adding a lot of boolean functions is a good idea? I s= omehow feel better with more usual int functions with -errno on failure. > > > > Bool is a good return value for functions which are boolean by nature: = checks, is something correspond to some criteria. But for reporting an erro= r I'd prefer -errno. >=20 > When would we want to return an errno? I thought the whole point of the > Error* was that that was where information about the error was returned. > If all your callsites are just going to do "if (ret < 0) { ... } then hav= ing > the functions pick an errno value to return is just extra work. IMHO errno should only be returned if the callers are likely to have=20 a genuine need to take action based on the errno in a way that isn't possible from the Error alone. I expect very few scenarios need that. Regards, Daniel --=20 |: 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= :|