From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58551) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dZfLt-0004Xv-Qn for qemu-devel@nongnu.org; Mon, 24 Jul 2017 11:32:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dZfLo-0002jK-E2 for qemu-devel@nongnu.org; Mon, 24 Jul 2017 11:32:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36698) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dZfLo-0002iX-4b for qemu-devel@nongnu.org; Mon, 24 Jul 2017 11:32:52 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC3FC624BB for ; Mon, 24 Jul 2017 15:32:48 +0000 (UTC) Date: Mon, 24 Jul 2017 12:32:42 -0300 From: Eduardo Habkost Message-ID: <20170724153242.GH2757@localhost.localdomain> References: <20170720162815.19802-1-ldoktor@redhat.com> <20170720162815.19802-6-ldoktor@redhat.com> <20170720182753.GV2757@localhost.localdomain> <6701dad4-40a5-7287-a4b8-a22e19b90ce2@redhat.com> <20170721184227.GB2757@localhost.localdomain> <1ec2f684-ddbc-de62-e13b-58f54d92e27d@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1ec2f684-ddbc-de62-e13b-58f54d92e27d@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 05/11] qemu.py: Use custom exceptions rather than Exception List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?utf-8?B?THVrw6HFoQ==?= Doktor Cc: apahim@redhat.com, qemu-devel@nongnu.org, famz@redhat.com, armbru@redhat.com, mreitz@redhat.com On Mon, Jul 24, 2017 at 02:13:09PM +0200, Luk=C3=A1=C5=A1 Doktor wrote: > Dne 21.7.2017 v 20:42 Eduardo Habkost napsal(a): > > On Fri, Jul 21, 2017 at 08:37:34AM +0200, Luk=C3=A1=C5=A1 Doktor wrot= e: > >> Dne 20.7.2017 v 20:27 Eduardo Habkost napsal(a): > >>> On Thu, Jul 20, 2017 at 06:28:09PM +0200, Luk=C3=A1=C5=A1 Doktor wr= ote: > >>>> The naked Exception should not be widely used. It makes sense to b= e a > >>>> bit more specific and use better-suited custom exceptions. As a be= nefit > >>>> we can store the full reply in the exception in case someone needs= it > >>>> when catching the exception. > >>>> > >>>> Signed-off-by: Luk=C3=A1=C5=A1 Doktor > >>>> --- > >>>> scripts/qemu.py | 17 +++++++++++++++-- > >>>> 1 file changed, 15 insertions(+), 2 deletions(-) > >>>> > >>>> diff --git a/scripts/qemu.py b/scripts/qemu.py > >>>> index 5948e19..2bd522f 100644 > >>>> --- a/scripts/qemu.py > >>>> +++ b/scripts/qemu.py > >>>> @@ -19,6 +19,19 @@ import subprocess > >>>> import qmp.qmp > >>>> =20 > >>>> =20 > >>>> +class MonitorResponseError(qmp.qmp.QMPError): > >>>> + ''' > >>>> + Represents erroneous QMP monitor reply > >>>> + ''' > >>>> + def __init__(self, reply): > >>>> + try: > >>>> + desc =3D reply["error"]["desc"] > >>>> + except KeyError: > >>>> + desc =3D reply > >>>> + super(MonitorResponseError, self).__init__(desc) > >>>> + self.reply =3D reply > >>> > >>> This would require every user of self.reply to first check if > >>> it's a string or dictionary. All because of the "Monitor is > >>> closed" case below: > >>> > >> I haven't used it for the `Monitor is closed` exception, so > >> it's just to be able to store really broken reply safely. > >> Anyway people can check whether the reply is a dict, or I can > >> add `is_valid_reply` property which would check for > >> `[error][desc]` presence (which is a bit more precise than just > >> plain dict type checking). > >=20 > >=20 > > Oops, I wasn't paying enough attention, sorry. self.reply is > > actually always set to the response from the monitor. > >=20 > > If you are just trying a safe fallback for 'desc' if the response > > broken, what about using repr(reply) or json.dumps(reply) if > > reply['error']['desc'] isn't set? > >=20 > I could use repr, but I'd prefer keeping it the way it is as > you could use `isinstance` to see whether it's dict and > interact with it (if needed, eg. on negative testing, which is > my motivation for storing the full response). This makes sense for self.reply, but I'm thinking about the argument to Exception.__init__(). I'm worried that things might break if the argument is not a string. --=20 Eduardo