bpo-46066: Deprecate kwargs syntax for TypedDict definitions

Doc/library/typing.rst

@@ -1389,11 +1389,20 @@ These are not used in annotations. They are building blocks for declaring types.
  ``Point2D.__optional_keys__``.
  To allow using this feature with older versions of Python that do not
  support :pep:`526`, ``TypedDict`` supports two additional equivalent
- syntactic forms::
+ syntactic forms:
+
+ * Using a literal :class:`dict` as the second argument::
 
- Point2D = TypedDict('Point2D', x=int, y=int, label=str)
  Point2D = TypedDict('Point2D',{'x': int, 'y': int, 'label': str})
 
+ * Using keyword arguments::
+
+ Point2D = TypedDict('Point2D', x=int, y=int, label=str)
+
+ .. deprecated-removed:: 3.11 3.13
+ The keyword-argument syntax is deprecated in 3.11 and will be removed
+ in 3.13. It may also be unsupported by static type checkers.
+
  By default, all keys must be present in a ``TypedDict``. It is possible to
  override this by specifying totality.
  Usage::
@@ -1402,6 +1411,9 @@ These are not used in annotations. They are building blocks for declaring types.
  x: int
  y: int
 
+ # Alternative syntax
+ Point2D = TypedDict('Point2D',{'x': int, 'y': int}, total=False)
+
  This means that a ``Point2D`` ``TypedDict`` can have any of the keys
  omitted. A type checker is only expected to support a literal ``False`` or
  ``True`` as the value of the ``total`` argument. ``True`` is the default,

Lib/test/test_typing.py

@@ -4300,7 +4300,8 @@ def test_basics_functional_syntax(self):
  self.assertEqual(Emp.__total__, True)
 
  def test_basics_keywords_syntax(self):
- Emp = TypedDict('Emp', name=str, id=int)
+ with self.assertWarns(DeprecationWarning):
+ Emp = TypedDict('Emp', name=str, id=int)
  self.assertIsSubclass(Emp, dict)
  self.assertIsSubclass(Emp, typing.MutableMapping)
  self.assertNotIsSubclass(Emp, collections.abc.Sequence)
@@ -4315,7 +4316,8 @@ def test_basics_keywords_syntax(self):
  self.assertEqual(Emp.__total__, True)
 
  def test_typeddict_special_keyword_names(self):
- TD = TypedDict("TD", cls=type, self=object, typename=str, _typename=int, fields=list, _fields=dict)
+ with self.assertWarns(DeprecationWarning):
+ TD = TypedDict("TD", cls=type, self=object, typename=str, _typename=int, fields=list, _fields=dict)
  self.assertEqual(TD.__name__, 'TD')
  self.assertEqual(TD.__annotations__,{'cls': type, 'self': object, 'typename': str, '_typename': int, 'fields': list, '_fields': dict})
  a = TD(cls=str, self=42, typename='foo', _typename=53, fields=[('bar', tuple)], _fields={'baz', set})
@@ -4371,7 +4373,7 @@ def test_py36_class_syntax_usage(self):
 
  def test_pickle(self):
  global EmpD # pickle wants to reference the class by name
- EmpD = TypedDict('EmpD', name=str, id=int)
+ EmpD = TypedDict('EmpD', {'name': str, 'id': int})
  jane = EmpD({'name': 'jane', 'id': 37})
  for proto in range(pickle.HIGHEST_PROTOCOL + 1):
  z = pickle.dumps(jane, proto)
@@ -4383,7 +4385,7 @@ def test_pickle(self):
  self.assertEqual(EmpDnew({'name': 'jane', 'id': 37}), jane)
 
  def test_optional(self):
- EmpD = TypedDict('EmpD', name=str, id=int)
+ EmpD = TypedDict('EmpD', {'name': str, 'id': int})
 
  self.assertEqual(typing.Optional[EmpD], typing.Union[None, EmpD])
  self.assertNotEqual(typing.List[EmpD], typing.Tuple[EmpD])

Lib/typing.py

@@ -2399,9 +2399,8 @@ class Point2D(TypedDict):
 
  The type info can be accessed via the Point2D.__annotations__ dict, and
  the Point2D.__required_keys__ and Point2D.__optional_keys__ frozensets.
- TypedDict supports two additional equivalent forms::
+ TypedDict supports an additional equivalent form::
 
- Point2D = TypedDict('Point2D', x=int, y=int, label=str)
  Point2D = TypedDict('Point2D',{'x': int, 'y': int, 'label': str})
 
  By default, all keys must be present in a TypedDict. It is possible
@@ -2417,14 +2416,22 @@ class point2D(TypedDict, total=False):
  the total argument. True is the default, and makes all items defined in the
  class body be required.
 
- The class syntax is only supported in Python 3.6+, while two other
- syntax forms work for Python 2.7 and 3.2+
+ The class syntax is only supported in Python 3.6+, while the other
+ syntax form works for Python 2.7 and 3.2+
  """
  if fields is None:
  fields = kwargs
  elif kwargs:
  raise TypeError("TypedDict takes either a dict or keyword arguments,"
  " but not both")
+ if kwargs:
+ warnings.warn(
+ "The kwargs-based syntax for TypedDict definitions is deprecated "
+ "in Python 3.11, will be removed in Python 3.13, and may not be "
+ "understood by third-party type checkers.",
+ DeprecationWarning,
+ stacklevel=2,
+ )
 
  ns ={'__annotations__': dict(fields)}
  module = _caller()

Misc/ACKS

@@ -1973,6 +1973,7 @@ Arnon Yaari
 Alakshendra Yadav
 Hirokazu Yamamoto
 Masayuki Yamamoto
+Jingchen Ye
 Ka-Ping Yee
 Chi Hsuan Yen
 Jason Yeo

Misc/NEWS.d/next/Library/2022-02-08-16-42-20.bpo-46066.m32Hl0.rst

@@ -0,0 +1,3 @@
+Deprecate kwargs-based syntax for :class:`typing.TypedDict` definitions.
+It had confusing semantics when specifying totality, and was largely unused.
+Patch by Jingchen Ye.