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Fix copying generic instances in Python 3 #502

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ilevkivskyi merged 2 commits into from
Nov 25, 2017
Merged

Fix copying generic instances in Python 3 #502

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652e6d1
Fix copying generic instances in Python 3
ilevkivskyi Nov 25, 2017
42b1697
Another ad-hoc fix for Python 2
ilevkivskyi Nov 25, 2017
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24 changes: 24 additions & 0 deletions python2/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1024,6 +1024,30 @@ class Node(Generic[T]): pass
self.assertEqual(t, deepcopy(t))
self.assertEqual(t, copy(t))

def test_copy_generic_instances(self):
T = TypeVar('T')
class C(Generic[T]):
def __init__(self, attr):
self.attr = attr

c = C(42)
self.assertEqual(copy(c).attr, 42)
self.assertEqual(deepcopy(c).attr, 42)
self.assertIsNot(copy(c), c)
self.assertIsNot(deepcopy(c), c)
c.attr = 1
self.assertEqual(copy(c).attr, 1)
self.assertEqual(deepcopy(c).attr, 1)
ci = C[int](42)
self.assertEqual(copy(ci).attr, 42)
self.assertEqual(deepcopy(ci).attr, 42)
self.assertIsNot(copy(ci), ci)
self.assertIsNot(deepcopy(ci), ci)
ci.attr = 1
self.assertEqual(copy(ci).attr, 1)
self.assertEqual(deepcopy(ci).attr, 1)
self.assertEqual(ci.__orig_class__, C[int])

def test_weakref_all(self):
T = TypeVar('T')
things = [Any, Union[T, int], Callable[..., T], Tuple[Any, Any],
Expand Down
22 changes: 17 additions & 5 deletions python2/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import re as stdlib_re # Avoid confusion with the re we export.
import sys
import types
import copy
try:
import collections.abc as collections_abc
except ImportError:
Expand Down Expand Up @@ -1253,11 +1254,6 @@ def __instancecheck__(self, instance):
return issubclass(instance.__class__, self)
return False

def __copy__(self):
return self.__class__(self.__name__, self.__bases__, dict(self.__dict__),
self.__parameters__, self.__args__, self.__origin__,
self.__extra__, self.__orig_bases__)

def __setattr__(self, attr, value):
# We consider all the subscripted genrics as proxies for original class
if (
Expand All @@ -1269,6 +1265,16 @@ def __setattr__(self, attr, value):
super(GenericMeta, self._gorg).__setattr__(attr, value)


def _copy_generic(self):
"""Hack to work around https://bugs.python.org/issue11480 on Python 2"""
return self.__class__(self.__name__, self.__bases__, dict(self.__dict__),
self.__parameters__, self.__args__, self.__origin__,
self.__extra__, self.__orig_bases__)


copy._copy_dispatch[GenericMeta] = _copy_generic


# Prevent checks for Generic to crash when defining Generic.
Generic = None

Expand Down Expand Up @@ -1365,6 +1371,9 @@ def __subclasscheck__(self, cls):
"with issubclass().")


copy._copy_dispatch[TupleMeta] = _copy_generic


class Tuple(tuple):
"""Tuple type; Tuple[X, Y] is the cross-product type of X and Y.

Expand Down Expand Up @@ -1443,6 +1452,9 @@ def __getitem_inner__(self, parameters):
return super(CallableMeta, self).__getitem__(parameters)


copy._copy_dispatch[CallableMeta] = _copy_generic


class Callable(object):
"""Callable type; Callable[[int], str] is a function of (int) -> str.

Expand Down
24 changes: 24 additions & 0 deletions src/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1080,6 +1080,30 @@ class Node(Generic[T]): ...
self.assertTrue(t is copy(t))
self.assertTrue(t is deepcopy(t))

def test_copy_generic_instances(self):
T = TypeVar('T')
class C(Generic[T]):
def __init__(self, attr: T) -> None:
self.attr = attr

c = C(42)
self.assertEqual(copy(c).attr, 42)
self.assertEqual(deepcopy(c).attr, 42)
self.assertIsNot(copy(c), c)
self.assertIsNot(deepcopy(c), c)
c.attr = 1
self.assertEqual(copy(c).attr, 1)
self.assertEqual(deepcopy(c).attr, 1)
ci = C[int](42)
self.assertEqual(copy(ci).attr, 42)
self.assertEqual(deepcopy(ci).attr, 42)
self.assertIsNot(copy(ci), ci)
self.assertIsNot(deepcopy(ci), ci)
ci.attr = 1
self.assertEqual(copy(ci).attr, 1)
self.assertEqual(deepcopy(ci).attr, 1)
self.assertEqual(ci.__orig_class__, C[int])

def test_weakref_all(self):
T = TypeVar('T')
things = [Any, Union[T, int], Callable[..., T], Tuple[Any, Any],
Expand Down
6 changes: 0 additions & 6 deletions src/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1160,12 +1160,6 @@ def __instancecheck__(self, instance):
# classes are supposed to be rare anyways.
return issubclass(instance.__class__, self)

def __copy__(self):
return self.__class__(self.__name__, self.__bases__,
_no_slots_copy(self.__dict__),
self.__parameters__, self.__args__, self.__origin__,
self.__extra__, self.__orig_bases__)

def __setattr__(self, attr, value):
# We consider all the subscripted generics as proxies for original class
if (
Expand Down