Issue #28556: allow default values in class form of NamedTuple -- Jelle Zijlstra (3.5->3.6)
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49f08a2c26
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@ -1400,6 +1400,10 @@ class G(Generic[T]):
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class CoolEmployee(NamedTuple):
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name: str
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cool: int
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class CoolEmployeeWithDefault(NamedTuple):
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name: str
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cool: int = 0
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"""
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if PY36:
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@ -1959,6 +1963,28 @@ class NamedTupleTests(BaseTestCase):
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collections.OrderedDict(name=str, cool=int))
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self.assertIs(CoolEmployee._field_types, CoolEmployee.__annotations__)
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@skipUnless(PY36, 'Python 3.6 required')
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def test_annotation_usage_with_default(self):
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jelle = CoolEmployeeWithDefault('Jelle')
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self.assertIsInstance(jelle, CoolEmployeeWithDefault)
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self.assertIsInstance(jelle, tuple)
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self.assertEqual(jelle.name, 'Jelle')
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self.assertEqual(jelle.cool, 0)
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cooler_employee = CoolEmployeeWithDefault('Sjoerd', 1)
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self.assertEqual(cooler_employee.cool, 1)
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self.assertEqual(CoolEmployeeWithDefault.__name__, 'CoolEmployeeWithDefault')
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self.assertEqual(CoolEmployeeWithDefault._fields, ('name', 'cool'))
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self.assertEqual(CoolEmployeeWithDefault._field_types, dict(name=str, cool=int))
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self.assertEqual(CoolEmployeeWithDefault._field_defaults, dict(cool=0))
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with self.assertRaises(TypeError):
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exec("""
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class NonDefaultAfterDefault(NamedTuple):
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x: int = 3
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y: int
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""")
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@skipUnless(PY36, 'Python 3.6 required')
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def test_namedtuple_keyword_usage(self):
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LocalEmployee = NamedTuple("LocalEmployee", name=str, age=int)
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@ -1959,7 +1959,22 @@ class NamedTupleMeta(type):
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raise TypeError("Class syntax for NamedTuple is only supported"
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" in Python 3.6+")
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types = ns.get('__annotations__', {})
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return _make_nmtuple(typename, types.items())
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nm_tpl = _make_nmtuple(typename, types.items())
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defaults = []
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defaults_dict = {}
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for field_name in types:
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if field_name in ns:
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default_value = ns[field_name]
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defaults.append(default_value)
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defaults_dict[field_name] = default_value
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elif defaults:
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raise TypeError("Non-default namedtuple field {field_name} cannot follow default"
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" field(s) {default_names}"
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.format(field_name=field_name,
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default_names=', '.join(defaults_dict.keys())))
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nm_tpl.__new__.__defaults__ = tuple(defaults)
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nm_tpl._field_defaults = defaults_dict
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return nm_tpl
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class NamedTuple(metaclass=NamedTupleMeta):
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"""Typed version of namedtuple.
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