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bpo-32226: Implementation of PEP 560 (core components) (#4732)
This part of the PEP implementation adds support for __mro_entries__ and __class_getitem__ by updating __build_class__ and PyObject_GetItem.
This commit is contained in:
Ivan Levkivskyi
GitHub
parent
15a8728415
commit
2b5fd1e9ca
7 changed files with 492 additions and 5 deletions
252
Lib/test/test_genericclass.py
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252
Lib/test/test_genericclass.py
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import unittest
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class TestMROEntry(unittest.TestCase):
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def test_mro_entry_signature(self):
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tested = []
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class B: ...
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class C:
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def __mro_entries__(self, *args, **kwargs):
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tested.extend([args, kwargs])
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return (C,)
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c = C()
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self.assertEqual(tested, [])
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class D(B, c): ...
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self.assertEqual(tested[0], ((B, c),))
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self.assertEqual(tested[1], {})
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def test_mro_entry(self):
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tested = []
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class A: ...
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class B: ...
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class C:
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def __mro_entries__(self, bases):
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tested.append(bases)
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return (self.__class__,)
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c = C()
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self.assertEqual(tested, [])
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class D(A, c, B): ...
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self.assertEqual(tested[-1], (A, c, B))
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self.assertEqual(D.__bases__, (A, C, B))
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self.assertEqual(D.__orig_bases__, (A, c, B))
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self.assertEqual(D.__mro__, (D, A, C, B, object))
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d = D()
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class E(d): ...
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self.assertEqual(tested[-1], (d,))
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self.assertEqual(E.__bases__, (D,))
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def test_mro_entry_none(self):
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tested = []
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class A: ...
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class B: ...
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class C:
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def __mro_entries__(self, bases):
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tested.append(bases)
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return ()
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c = C()
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self.assertEqual(tested, [])
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class D(A, c, B): ...
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self.assertEqual(tested[-1], (A, c, B))
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self.assertEqual(D.__bases__, (A, B))
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self.assertEqual(D.__orig_bases__, (A, c, B))
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self.assertEqual(D.__mro__, (D, A, B, object))
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class E(c): ...
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self.assertEqual(tested[-1], (c,))
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self.assertEqual(E.__bases__, (object,))
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self.assertEqual(E.__orig_bases__, (c,))
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self.assertEqual(E.__mro__, (E, object))
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def test_mro_entry_with_builtins(self):
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tested = []
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class A: ...
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class C:
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def __mro_entries__(self, bases):
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tested.append(bases)
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return (dict,)
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c = C()
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self.assertEqual(tested, [])
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class D(A, c): ...
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self.assertEqual(tested[-1], (A, c))
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self.assertEqual(D.__bases__, (A, dict))
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self.assertEqual(D.__orig_bases__, (A, c))
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self.assertEqual(D.__mro__, (D, A, dict, object))
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def test_mro_entry_with_builtins_2(self):
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tested = []
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class C:
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def __mro_entries__(self, bases):
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tested.append(bases)
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return (C,)
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c = C()
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self.assertEqual(tested, [])
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class D(c, dict): ...
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self.assertEqual(tested[-1], (c, dict))
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self.assertEqual(D.__bases__, (C, dict))
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self.assertEqual(D.__orig_bases__, (c, dict))
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self.assertEqual(D.__mro__, (D, C, dict, object))
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def test_mro_entry_errors(self):
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class C_too_many:
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def __mro_entries__(self, bases, something, other):
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return ()
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c = C_too_many()
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with self.assertRaises(TypeError):
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class D(c): ...
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class C_too_few:
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def __mro_entries__(self):
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return ()
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d = C_too_few()
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with self.assertRaises(TypeError):
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class D(d): ...
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def test_mro_entry_errors_2(self):
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class C_not_callable:
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__mro_entries__ = "Surprise!"
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c = C_not_callable()
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with self.assertRaises(TypeError):
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class D(c): ...
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class C_not_tuple:
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def __mro_entries__(self):
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return object
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c = C_not_tuple()
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with self.assertRaises(TypeError):
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class D(c): ...
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def test_mro_entry_metaclass(self):
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meta_args = []
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class Meta(type):
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def __new__(mcls, name, bases, ns):
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meta_args.extend([mcls, name, bases, ns])
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return super().__new__(mcls, name, bases, ns)
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class A: ...
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class C:
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def __mro_entries__(self, bases):
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return (A,)
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c = C()
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class D(c, metaclass=Meta):
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x = 1
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self.assertEqual(meta_args[0], Meta)
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self.assertEqual(meta_args[1], 'D')
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self.assertEqual(meta_args[2], (A,))
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self.assertEqual(meta_args[3]['x'], 1)
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self.assertEqual(D.__bases__, (A,))
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self.assertEqual(D.__orig_bases__, (c,))
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self.assertEqual(D.__mro__, (D, A, object))
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self.assertEqual(D.__class__, Meta)
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def test_mro_entry_type_call(self):
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# Substitution should _not_ happen in direct type call
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class C:
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def __mro_entries__(self, bases):
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return ()
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c = C()
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with self.assertRaisesRegex(TypeError,
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"MRO entry resolution; "
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"use types.new_class()"):
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type('Bad', (c,), {})
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class TestClassGetitem(unittest.TestCase):
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def test_class_getitem(self):
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getitem_args = []
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class C:
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def __class_getitem__(*args, **kwargs):
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getitem_args.extend([args, kwargs])
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return None
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C[int, str]
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self.assertEqual(getitem_args[0], (C, (int, str)))
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self.assertEqual(getitem_args[1], {})
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def test_class_getitem(self):
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class C:
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def __class_getitem__(cls, item):
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return f'C[{item.__name__}]'
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self.assertEqual(C[int], 'C[int]')
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self.assertEqual(C[C], 'C[C]')
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def test_class_getitem_inheritance(self):
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class C:
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def __class_getitem__(cls, item):
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return f'{cls.__name__}[{item.__name__}]'
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class D(C): ...
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self.assertEqual(D[int], 'D[int]')
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self.assertEqual(D[D], 'D[D]')
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def test_class_getitem_inheritance_2(self):
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class C:
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def __class_getitem__(cls, item):
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return 'Should not see this'
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class D(C):
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def __class_getitem__(cls, item):
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return f'{cls.__name__}[{item.__name__}]'
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self.assertEqual(D[int], 'D[int]')
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self.assertEqual(D[D], 'D[D]')
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def test_class_getitem_patched(self):
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class C:
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def __init_subclass__(cls):
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def __class_getitem__(cls, item):
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return f'{cls.__name__}[{item.__name__}]'
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cls.__class_getitem__ = __class_getitem__
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class D(C): ...
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self.assertEqual(D[int], 'D[int]')
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self.assertEqual(D[D], 'D[D]')
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def test_class_getitem_with_builtins(self):
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class A(dict):
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called_with = None
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def __class_getitem__(cls, item):
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cls.called_with = item
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class B(A):
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pass
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self.assertIs(B.called_with, None)
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B[int]
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self.assertIs(B.called_with, int)
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def test_class_getitem_errors(self):
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class C_too_few:
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def __class_getitem__(cls):
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return None
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with self.assertRaises(TypeError):
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C_too_few[int]
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class C_too_many:
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def __class_getitem__(cls, one, two):
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return None
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with self.assertRaises(TypeError):
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C_too_many[int]
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def test_class_getitem_errors_2(self):
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class C:
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def __class_getitem__(cls, item):
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return None
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with self.assertRaises(TypeError):
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C()[int]
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class E: ...
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e = E()
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e.__class_getitem__ = lambda cls, item: 'This will not work'
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with self.assertRaises(TypeError):
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e[int]
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class C_not_callable:
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__class_getitem__ = "Surprise!"
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with self.assertRaises(TypeError):
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C_not_callable[int]
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def test_class_getitem_metaclass(self):
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class Meta(type):
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def __class_getitem__(cls, item):
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return f'{cls.__name__}[{item.__name__}]'
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self.assertEqual(Meta[int], 'Meta[int]')
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def test_class_getitem_metaclass_2(self):
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class Meta(type):
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def __getitem__(cls, item):
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return 'from metaclass'
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class C(metaclass=Meta):
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def __class_getitem__(cls, item):
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return 'from __class_getitem__'
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self.assertEqual(C[int], 'from metaclass')
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if __name__ == "__main__":
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unittest.main()
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