On Fri, Jul 21, 2017 at 08:37:34AM +0200, Lukáš Doktor wrote: > Dne 20.7.2017 v 20:27 Eduardo Habkost napsal(a): > > On Thu, Jul 20, 2017 at 06:28:09PM +0200, Lukáš Doktor wrote: > >> The naked Exception should not be widely used. It makes sense to be a > >> bit more specific and use better-suited custom exceptions. As a benefit > >> we can store the full reply in the exception in case someone needs it > >> when catching the exception. > >> > >> Signed-off-by: Lukáš Doktor <ldok...@redhat.com> > >> --- > >> 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 > >> > >> > >> +class MonitorResponseError(qmp.qmp.QMPError): > >> + ''' > >> + Represents erroneous QMP monitor reply > >> + ''' > >> + def __init__(self, reply): > >> + try: > >> + desc = reply["error"]["desc"] > >> + except KeyError: > >> + desc = reply > >> + super(MonitorResponseError, self).__init__(desc) > >> + self.reply = 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).
Oops, I wasn't paying enough attention, sorry. self.reply is actually always set to the response from the monitor. 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? > > >> + > >> + > >> class QEMUMachine(object): > >> '''A QEMU VM''' > >> > >> @@ -197,9 +210,9 @@ class QEMUMachine(object): > >> ''' > >> reply = self.qmp(cmd, conv_keys, **args) > >> if reply is None: > >> - raise Exception("Monitor is closed") > >> + raise qmp.qmp.QMPError("Monitor is closed") > > > > Should we really use the same exception type for this, if it's > > not really a QMP monitor error reply, and won't even have a real > > QMP reply in self.reply? > > > I wasn't sure but the same exception can be caused by other > failures when obtaining replies so I think in case the monitor > is closed we might expect the same exception. Would importing > it in the top level of this module to become `qemu.QMPError` > work for you better, or would you prefer IOError, RuntimeError > or another custom exception? I was not paying enough attention. QMPError sounds good to me. Reviewed-by: Eduardo Habkost <ehabk...@redhat.com> > > Lukáš > > > > >> if "error" in reply: > >> - raise Exception(reply["error"]["desc"]) > >> + raise MonitorResponseError(reply) > >> return reply["return"] > >> > >> def get_qmp_event(self, wait=False): > >> -- > >> 2.9.4 > >> > > > > -- Eduardo