04.08.2021 19:27, John Snow wrote:

On Wed, Aug 4, 2021 at 5:39 AM Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com 
<mailto:vsement...@virtuozzo.com>> wrote:

    In superclass __enter__ method is defined with return value type hint
    'QEMUMachine'. So, mypy thinks that return value of VM.__enter__ is
    QEMUMachine. Let's redefine __enter__ in VM class, to give it correct
    type hint.

    Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com 
<mailto:vsement...@virtuozzo.com>>
    Reviewed-by: Max Reitz <mre...@redhat.com <mailto:mre...@redhat.com>>
    ---
      tests/qemu-iotests/iotests.py | 4 ++++
      1 file changed, 4 insertions(+)

    diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
    index 89663dac06..025e288ddd 100644
    --- a/tests/qemu-iotests/iotests.py
    +++ b/tests/qemu-iotests/iotests.py
    @@ -568,6 +568,10 @@ def remote_filename(path):
      class VM(qtest.QEMUQtestMachine):
          '''A QEMU VM'''

    +    # Redefine __enter__ with proper type hint
    +    def __enter__(self) -> 'VM':
    +        return self
    +
          def __init__(self, path_suffix=''):
              name = "qemu%s-%d" % (path_suffix, os.getpid())
              super().__init__(qemu_prog, qemu_opts, name=name,
-- 2.29.2


First and foremost:

Reviewed-by: John Snow <js...@redhat.com <mailto:js...@redhat.com>>
Acked-by: John Snow <js...@redhat.com <mailto:js...@redhat.com>>

A more durable approach might be to annotate QEMUMachine differently such that 
subclasses get the right types automatically. See if this following snippet 
works instead of adding a new __enter__ method.

diff --git a/python/qemu/machine/machine.py b/python/qemu/machine/machine.py
index 971ed7e8c6a..2e410103569 100644
--- a/python/qemu/machine/machine.py
+++ b/python/qemu/machine/machine.py
@@ -36,6 +36,7 @@
      Sequence,
      Tuple,
      Type,
+    TypeVar,
  )

  from qemu.qmp import (  # pylint: disable=import-error
@@ -73,6 +74,9 @@ class AbnormalShutdown(QEMUMachineError):
      """


+_T = TypeVar('_T', bound='QEMUMachine')
+
+
  class QEMUMachine:
      """
      A QEMU VM.
@@ -166,7 +170,7 @@ def __init__(self,
          self._remove_files: List[str] = []
          self._user_killed = False

-    def __enter__(self) -> 'QEMUMachine':
+    def __enter__(self: _T) -> _T:
          return self

      def __exit__(self,
@@ -182,8 +186,8 @@ def add_monitor_null(self) -> None:
          self._args.append('-monitor')
          self._args.append('null')

-    def add_fd(self, fd: int, fdset: int,
-               opaque: str, opts: str = '') -> 'QEMUMachine':
+    def add_fd(self: _T, fd: int, fdset: int,
+               opaque: str, opts: str = '') -> _T:
          """
          Pass a file descriptor to the VM
          """

That looks better, I'll go this way, thanks!

--
Best regards,
Vladimir

Reply via email to