From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>,
"Eduardo Habkost" <ehabkost@redhat.com>,
"John Snow" <jsnow@redhat.com>,
"Ahmed Karaman" <ahmedkhaledkaraman@gmail.com>,
"Cleber Rosa" <crosa@redhat.com>,
"Philippe Mathieu-Daudé" <philmd@redhat.com>
Subject: [PULL 18/19] python/qmp.py: add casts to JSON deserialization
Date: Wed, 15 Jul 2020 00:21:31 +0200 [thread overview]
Message-ID: <20200714222132.10815-19-philmd@redhat.com> (raw)
In-Reply-To: <20200714222132.10815-1-philmd@redhat.com>
From: John Snow <jsnow@redhat.com>
mypy and python type hints are not powerful enough to properly describe
JSON messages in Python 3.6. The best we can do, generally, is describe
them as Dict[str, Any].
Add casts to coerce this type for static analysis; but do NOT enforce
this type at runtime in any way.
Note: Python 3.8 adds a TypedDict construct which allows for the
description of more arbitrary Dictionary shapes. There is a third-party
module, "Pydantic", which is compatible with 3.6 that can be used
instead of the JSON library that parses JSON messages to fully-typed
Python objects, and may be preferable in some cases.
(That is well beyond the scope of this commit or series.)
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20200710052220.3306-6-jsnow@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
python/qemu/qmp.py | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/python/qemu/qmp.py b/python/qemu/qmp.py
index ef3c919b76..1ae36050a4 100644
--- a/python/qemu/qmp.py
+++ b/python/qemu/qmp.py
@@ -13,6 +13,7 @@
import logging
from typing import (
Any,
+ cast,
Dict,
Optional,
TextIO,
@@ -130,7 +131,10 @@ def __json_read(self, only_event=False):
data = self.__sockfile.readline()
if not data:
return None
- resp = json.loads(data)
+ # By definition, any JSON received from QMP is a QMPMessage,
+ # and we are asserting only at static analysis time that it
+ # has a particular shape.
+ resp: QMPMessage = json.loads(data)
if 'event' in resp:
self.logger.debug("<<< %s", resp)
self.__events.append(resp)
@@ -262,7 +266,7 @@ def command(self, cmd, **kwds):
ret = self.cmd(cmd, kwds)
if 'error' in ret:
raise QMPResponseError(ret)
- return ret['return']
+ return cast(QMPReturnValue, ret['return'])
def pull_event(self, wait=False):
"""
--
2.21.3
next prev parent reply other threads:[~2020-07-14 22:33 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-14 22:21 [PULL 00/19] Python patches for 5.1 Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 01/19] scripts/performance: Add dissect.py script Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 02/19] python/machine.py: consolidate _post_shutdown() Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 03/19] python/machine.py: Close QMP socket in cleanup Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 04/19] python/machine.py: Add _early_cleanup hook Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 05/19] python/machine.py: Perform early cleanup for wait() calls, too Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 06/19] python/machine.py: Prohibit multiple shutdown() calls Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 07/19] python/machine.py: Add a configurable timeout to shutdown() Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 08/19] python/machine.py: Make wait() call shutdown() Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 09/19] tests/acceptance: wait() instead of shutdown() where appropriate Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 10/19] tests/acceptance: Don't test reboot on cubieboard Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 11/19] python/machine.py: split shutdown into hard and soft flavors Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 12/19] python/machine.py: re-add sigkill warning suppression Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 13/19] python/machine.py: change default wait timeout to 3 seconds Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 14/19] python/qmp.py: Define common types Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 15/19] iotests.py: use qemu.qmp type aliases Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 16/19] python/qmp.py: re-absorb MonitorResponseError Philippe Mathieu-Daudé
2020-07-14 22:21 ` [PULL 17/19] python/qmp.py: Do not return None from cmd_obj Philippe Mathieu-Daudé
2020-07-14 22:21 ` Philippe Mathieu-Daudé [this message]
2020-07-14 22:21 ` [PULL 19/19] python/qmp.py: add QMPProtocolError Philippe Mathieu-Daudé
2020-07-15 12:53 ` [PULL 00/19] Python patches for 5.1 Peter Maydell
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