From 33708e76578c173333d1879a4a21baddf8fcdb6a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20G=C3=B3rny?= <mgorny@gentoo.org>
Date: Fri, 29 May 2020 16:06:07 +0200
Subject: [PATCH] Update for fixed outer @classmethod behavior in Python 3.9
Fixes #160
---
docs/decorators.rst | 18 ++++++-------
tests/test_outer_classmethod.py | 45 +++++++++++++++++++++------------
tests/test_synchronized_lock.py | 22 ++++++++--------
3 files changed, 49 insertions(+), 36 deletions(-)
diff --git a/docs/decorators.rst b/docs/decorators.rst
index b8200d6..94201de 100644
--- a/docs/decorators.rst
+++ b/docs/decorators.rst
@@ -641,15 +641,15 @@ When calling the wrapped function in the decorator wrapper function, the
instance is already bound to ``wrapped`` and will be passed automatically
as the first argument to the original wrapped function.
-Note that due to a bug in Python ``classmethod.__get__()``, whereby it does
-not apply the descriptor protocol to the function wrapped by ``@classmethod``,
-the above only applies where the decorator wraps the ``@classmethod``
-decorator. If the decorator is placed inside of the ``@classmethod``
-decorator, then ``instance`` will be ``None`` and the decorator wrapper
-function will see the call as being the same as a normal function. As a
-result, always place any decorator outside of the ``@classmethod``
-decorator. Hopefully this issue in Python can be addressed in a future
-Python version.
+Note that due to a bug in Python prior to 3.9 ``classmethod.__get__()``,
+whereby it does not apply the descriptor protocol to the function
+wrapped by ``@classmethod``, the above only applies where the decorator
+wraps the ``@classmethod`` decorator. If the decorator is placed inside
+of the ``@classmethod`` decorator, then ``instance`` will be ``None``
+and the decorator wrapper function will see the call as being the same
+as a normal function. As a result, always place any decorator outside of
+the ``@classmethod`` decorator if you need to support earlier Python
+versions.
Decorating Static Methods
-------------------------
diff --git a/tests/test_outer_classmethod.py b/tests/test_outer_classmethod.py
index 6b4af4f..9c2fcb8 100644
--- a/tests/test_outer_classmethod.py
+++ b/tests/test_outer_classmethod.py
@@ -3,6 +3,7 @@
import unittest
import inspect
import imp
+import sys
import wrapt
@@ -121,20 +122,26 @@ def test_instance_isinstance(self):
class TestCallingOuterClassMethod(unittest.TestCase):
def test_class_call_function(self):
- # Test calling classmethod. The instance and class passed to the
- # wrapper will both be None because our decorator is surrounded
- # by the classmethod decorator. The classmethod decorator
- # doesn't bind the method and treats it like a normal function,
- # explicitly passing the class as the first argument with the
- # actual arguments following that.
+ # Test calling classmethod. In Python 3.9, the class will be
+ # passed as instance. In older versions of Python, the instance
+ # and class passed to the wrapper will both be None because our
+ # decorator is surrounded by the classmethod decorator.
+ # The classmethod decorator doesn't bind the method and treats
+ # it like a normal function, explicitly passing the class
+ # as the first argument with the actual arguments following
+ # that.
_args = (1, 2)
_kwargs = {'one': 1, 'two': 2}
@wrapt.decorator
def _decorator(wrapped, instance, args, kwargs):
- self.assertEqual(instance, None)
- self.assertEqual(args, (Class,)+_args)
+ if sys.hexversion >= 0x03090000:
+ self.assertEqual(instance, Class)
+ self.assertEqual(args, _args)
+ else:
+ self.assertEqual(instance, None)
+ self.assertEqual(args, (Class,)+_args)
self.assertEqual(kwargs, _kwargs)
self.assertEqual(wrapped.__module__, _function.__module__)
self.assertEqual(wrapped.__name__, _function.__name__)
@@ -155,20 +162,26 @@ def _function(cls, *args, **kwargs):
self.assertEqual(result, (_args, _kwargs))
def test_instance_call_function(self):
- # Test calling classmethod via class instance. The instance
- # and class passed to the wrapper will both be None because our
- # decorator is surrounded by the classmethod decorator. The
- # classmethod decorator doesn't bind the method and treats it
- # like a normal function, explicitly passing the class as the
- # first argument with the actual arguments following that.
+ # Test calling classmethod via class instance. In Python 3.9,
+ # the class will be passed as instance. In older versions
+ # of Python, the instance and class passed to the wrapper will
+ # both be None because our decorator is surrounded
+ # by the classmethod decorator. The classmethod decorator
+ # doesn't bind the method and treats it like a normal function,
+ # explicitly passing the class as the first argument with
+ # the actual arguments following that.
_args = (1, 2)
_kwargs = {'one': 1, 'two': 2}
@wrapt.decorator
def _decorator(wrapped, instance, args, kwargs):
- self.assertEqual(instance, None)
- self.assertEqual(args, (Class,)+_args)
+ if sys.hexversion >= 0x03090000:
+ self.assertEqual(instance, Class)
+ self.assertEqual(args, _args)
+ else:
+ self.assertEqual(instance, None)
+ self.assertEqual(args, (Class,)+_args)
self.assertEqual(kwargs, _kwargs)
self.assertEqual(wrapped.__module__, _function.__module__)
self.assertEqual(wrapped.__name__, _function.__name__)
diff --git a/tests/test_synchronized_lock.py b/tests/test_synchronized_lock.py
index 6e7eb12..b8f60f3 100644
--- a/tests/test_synchronized_lock.py
+++ b/tests/test_synchronized_lock.py
@@ -1,5 +1,6 @@
from __future__ import print_function
+import sys
import unittest
import wrapt
@@ -157,34 +158,33 @@ def test_synchronized_inner_classmethod(self):
self.assertEqual(_lock3, _lock2)
def test_synchronized_outer_classmethod(self):
- # XXX If all was good, this would be detected as a class
+ # Bug in Python < 3.9:
+ # If all was good, this would be detected as a class
# method call, but the classmethod decorator doesn't bind
# the wrapped function to the class before calling and
# just calls it direct, explicitly passing the class as
- # first argument. This screws things up. Would be nice if
- # Python were fixed, but that isn't likely to happen.
+ # first argument. This screws things up.
- #_lock0 = getattr(C4, '_synchronized_lock', None)
- _lock0 = getattr(C4.function2, '_synchronized_lock', None)
+ lock_target = (C4 if sys.hexversion >= 0x03090000
+ else C4.function2)
+
+ _lock0 = getattr(lock_target, '_synchronized_lock', None)
self.assertEqual(_lock0, None)
c4.function2()
- #_lock1 = getattr(C4, '_synchronized_lock', None)
- _lock1 = getattr(C4.function2, '_synchronized_lock', None)
+ _lock1 = getattr(lock_target, '_synchronized_lock', None)
self.assertNotEqual(_lock1, None)
C4.function2()
- #_lock2 = getattr(C4, '_synchronized_lock', None)
- _lock2 = getattr(C4.function2, '_synchronized_lock', None)
+ _lock2 = getattr(lock_target, '_synchronized_lock', None)
self.assertNotEqual(_lock2, None)
self.assertEqual(_lock2, _lock1)
C4.function2()
- #_lock3 = getattr(C4, '_synchronized_lock', None)
- _lock3 = getattr(C4.function2, '_synchronized_lock', None)
+ _lock3 = getattr(lock_target, '_synchronized_lock', None)
self.assertNotEqual(_lock3, None)
self.assertEqual(_lock3, _lock2)