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Date: Thu, 31 Jul 2014 15:49:30 +0100
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 4/7] a trivial code change for more
 idiomatic writing style
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: "Huangweidong (C)" <weidong.huang@huawei.com>, Stefan Hajnoczi <stefanha@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.a@redhat.com>, Luonengjun <luonengjun@huawei.com>, QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Vassili Karpov <av1474@comtv.ru>, Gerd Hoffmann <kraxel@redhat.com>, Anthony Liguori <aliguori@amazon.com>, Igor Mammedov <imammedo@redhat.com>, Dmitry Fleytman <dmitry@daynix.com>, Paolo Bonzini <pbonzini@redhat.com>, peter.huangpeng@huawei.com, Luiz Capitulino <lcapitulino@redhat.com>, Andreas F?rber <afaerber@suse.de>

* Peter Maydell (peter.maydell@linaro.org) wrote:
> On 31 July 2014 14:55, Dr. David Alan Gilbert <dgilbert@redhat.com> wrote:
> > * arei.gonglei@huawei.com (arei.gonglei@huawei.com) wrote:
> >> --- a/qdev-monitor.c
> >> +++ b/qdev-monitor.c
> >> @@ -694,7 +694,7 @@ void qmp_device_del(const char *id, Error **errp)
> >>      DeviceState *dev;
> >>
> >>      dev = qdev_find_recursive(sysbus_get_default(), id);
> >> -    if (NULL == dev) {
> >> +    if (dev == NULL) {
> >
> > I know people who write it as 'NULL == dev' on purpose,
> > because that will cause an error if you accidentally type a single =
> > where as 'dev = NULL'  will just cause confusion.
> 
> Yes, this is the motivation for Yoda conditionals. But it only
> makes sense if you don't have a compiler with a sensible
> warning configuration. For QEMU you will get an error if you
> write "dev = NULL" :
> 
> error: suggest parentheses around assignment used as truth value
> [-Werror=parentheses]
> 
> so we don't need to get people to contort their code like this.


OK, that's fair enough.

Dave

> thanks
> -- PMM
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK