Re: [Qemu-devel] [PATCH 10/10] qemu-iotests/118: Test media change with qdev name

From: Sascha Silbe <silbe@linux.vnet.ibm.com>
To: Eric Blake <eblake@redhat.com>, Kevin Wolf <kwolf@redhat.com>,
	qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org, mreitz@redhat.com
Subject: Re: [Qemu-devel] [PATCH 10/10] qemu-iotests/118: Test media change with qdev name
Date: Thu, 15 Sep 2016 19:57:41 +0200	[thread overview]
Message-ID: <87h99hcaga.fsf@oc4731375738.ibm.com> (raw)
In-Reply-To: <28a951bf-d082-a7c8-41af-38cccb0a9185@redhat.com>

Dear Eric,

Eric Blake <eblake@redhat.com> writes:

> arglist = (all other parameters)
> if self.device_name:
>     arglist.append(id=self.device_name)
> else:
>     arglist.append(device='drive0')
> invoke(self.vm.qmp, arglist)

That would be:

        qmp_args = {'cmd': 'blockdev-change-medium', 'filename': new_img,
                    'format': iotests.imgfmt}
        if self.device_name is not None:
            qmp_args['id'] = self.device_name
        else:
            qmp_args['device'] = 'drive0'
        result = self.vm.qmp(**qmp_args)

Or:

        qmp_args = {'filename': new_img, 'format': iotests.imgfmt}
        if self.device_name is not None:
            qmp_args['id'] = self.device_name
        else:
            qmp_args['device'] = 'drive0'
        result = self.vm.qmp('blockdev-change-medium', **qmp_args)

FWIW these days I tend to use Python magics (like *args / **kwargs) only
if there's a _significant_ improvement in either functionality or
readability; especially for code bases that are being worked on by
developers who don't speak Python "natively". Using magics sparingly
also makes it easier for static analysis tools like pylint.

Sascha
-- 
Softwareentwicklung Sascha Silbe, Niederhofenstraße 5/1, 71229 Leonberg
https://se-silbe.de/
USt-IdNr. DE281696641