diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index 54cc3ea3311adf..dd8ea3c364f49a 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -3500,20 +3500,11 @@ Introspection helpers Evaluate an :class:`annotationlib.ForwardRef` as a :term:`type hint`. This is similar to calling :meth:`annotationlib.ForwardRef.evaluate`, - but unlike that method, :func:`!evaluate_forward_ref` also: - - * Recursively evaluates forward references nested within the type hint. - * Raises :exc:`TypeError` when it encounters certain objects that are - not valid type hints. - * Replaces type hints that evaluate to :const:`!None` with - :class:`types.NoneType`. - * Supports the :attr:`~annotationlib.Format.FORWARDREF` and - :attr:`~annotationlib.Format.STRING` formats. + but unlike that method, :func:`!evaluate_forward_ref` also + recursively evaluates forward references nested within the type hint. See the documentation for :meth:`annotationlib.ForwardRef.evaluate` for - the meaning of the *owner*, *globals*, *locals*, and *type_params* parameters. - *format* specifies the format of the annotation and is a member of - the :class:`annotationlib.Format` enum. + the meaning of the *owner*, *globals*, *locals*, *type_params*, and *format* parameters. .. versionadded:: 3.14 diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py index 6ef633e4545aef..6c6a162531f984 100644 --- a/Lib/test/test_typing.py +++ b/Lib/test/test_typing.py @@ -6859,12 +6859,10 @@ def test_forward_ref_and_final(self): self.assertEqual(hints, {'value': Final}) def test_top_level_class_var(self): - # https://bugs.python.org/issue45166 - with self.assertRaisesRegex( - TypeError, - r'typing.ClassVar\[int\] is not valid as type argument', - ): - get_type_hints(ann_module6) + # This is not meaningful but we don't raise for it. + # https://github.com/python/cpython/issues/133959 + hints = get_type_hints(ann_module6) + self.assertEqual(hints, {'wrong': ClassVar[int]}) def test_get_type_hints_typeddict(self): self.assertEqual(get_type_hints(TotalMovie), {'title': str, 'year': int}) @@ -6967,6 +6965,11 @@ def foo(a: 'Callable[..., T]'): self.assertEqual(get_type_hints(foo, globals(), locals()), {'a': Callable[..., T]}) + def test_special_forms_no_forward(self): + def f(x: ClassVar[int]): + pass + self.assertEqual(get_type_hints(f), {'x': ClassVar[int]}) + def test_special_forms_forward(self): class C: @@ -6982,8 +6985,9 @@ class CF: self.assertEqual(get_type_hints(C, globals())['b'], Final[int]) self.assertEqual(get_type_hints(C, globals())['x'], ClassVar) self.assertEqual(get_type_hints(C, globals())['y'], Final) - with self.assertRaises(TypeError): - get_type_hints(CF, globals()), + lfi = get_type_hints(CF, globals())['b'] + self.assertIs(get_origin(lfi), list) + self.assertEqual(get_args(lfi), (Final[int],)) def test_union_forward_recursion(self): ValueList = List['Value'] @@ -7216,33 +7220,112 @@ class C(Generic[T]): pass class EvaluateForwardRefTests(BaseTestCase): def test_evaluate_forward_ref(self): int_ref = ForwardRef('int') - missing = ForwardRef('missing') + self.assertIs(typing.evaluate_forward_ref(int_ref), int) self.assertIs( typing.evaluate_forward_ref(int_ref, type_params=()), int, ) + self.assertIs( + typing.evaluate_forward_ref(int_ref, format=annotationlib.Format.VALUE), + int, + ) self.assertIs( typing.evaluate_forward_ref( - int_ref, type_params=(), format=annotationlib.Format.FORWARDREF, + int_ref, format=annotationlib.Format.FORWARDREF, ), int, ) + self.assertEqual( + typing.evaluate_forward_ref( + int_ref, format=annotationlib.Format.STRING, + ), + 'int', + ) + + def test_evaluate_forward_ref_undefined(self): + missing = ForwardRef('missing') + with self.assertRaises(NameError): + typing.evaluate_forward_ref(missing) self.assertIs( typing.evaluate_forward_ref( - missing, type_params=(), format=annotationlib.Format.FORWARDREF, + missing, format=annotationlib.Format.FORWARDREF, ), missing, ) self.assertEqual( typing.evaluate_forward_ref( - int_ref, type_params=(), format=annotationlib.Format.STRING, + missing, format=annotationlib.Format.STRING, ), - 'int', + "missing", ) - def test_evaluate_forward_ref_no_type_params(self): - ref = ForwardRef('int') - self.assertIs(typing.evaluate_forward_ref(ref), int) + def test_evaluate_forward_ref_nested(self): + ref = ForwardRef("int | list['str']") + self.assertEqual( + typing.evaluate_forward_ref(ref), + int | list[str], + ) + self.assertEqual( + typing.evaluate_forward_ref(ref, format=annotationlib.Format.FORWARDREF), + int | list[str], + ) + self.assertEqual( + typing.evaluate_forward_ref(ref, format=annotationlib.Format.STRING), + "int | list['str']", + ) + + why = ForwardRef('"\'str\'"') + self.assertIs(typing.evaluate_forward_ref(why), str) + + def test_evaluate_forward_ref_none(self): + none_ref = ForwardRef('None') + self.assertIs(typing.evaluate_forward_ref(none_ref), None) + + def test_globals(self): + A = "str" + ref = ForwardRef('list[A]') + with self.assertRaises(NameError): + typing.evaluate_forward_ref(ref) + self.assertEqual( + typing.evaluate_forward_ref(ref, globals={'A': A}), + list[str], + ) + + def test_owner(self): + ref = ForwardRef("A") + + with self.assertRaises(NameError): + typing.evaluate_forward_ref(ref) + + # Now should pick up the globals of this module + self.assertIs( + typing.evaluate_forward_ref(ref, owner=Loop), A + ) + + def test_inherited_owner(self): + # owner passed to evaluate_forward_ref + ref = ForwardRef("list['A']") + self.assertEqual( + typing.evaluate_forward_ref(ref, owner=Loop), + list[A], + ) + + # owner set on the ForwardRef + ref = ForwardRef("list['A']", owner=Loop) + self.assertEqual( + typing.evaluate_forward_ref(ref), + list[A], + ) + + def test_partial_evaluation(self): + ref = ForwardRef("list[A]") + with self.assertRaises(NameError): + typing.evaluate_forward_ref(ref) + + self.assertEqual( + typing.evaluate_forward_ref(ref, format=annotationlib.Format.FORWARDREF), + list[EqualToForwardRef('A')], + ) class CollectionsAbcTests(BaseTestCase): diff --git a/Lib/typing.py b/Lib/typing.py index 3d64480e1431c1..ea6554152b2b3d 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -956,12 +956,8 @@ def evaluate_forward_ref( """Evaluate a forward reference as a type hint. This is similar to calling the ForwardRef.evaluate() method, - but unlike that method, evaluate_forward_ref() also: - - * Recursively evaluates forward references nested within the type hint. - * Rejects certain objects that are not valid type hints. - * Replaces type hints that evaluate to None with types.NoneType. - * Supports the *FORWARDREF* and *STRING* formats. + but unlike that method, evaluate_forward_ref() also + recursively evaluates forward references nested within the type hint. *forward_ref* must be an instance of ForwardRef. *owner*, if given, should be the object that holds the annotations that the forward reference @@ -981,23 +977,24 @@ def evaluate_forward_ref( if forward_ref.__forward_arg__ in _recursive_guard: return forward_ref - try: - value = forward_ref.evaluate(globals=globals, locals=locals, - type_params=type_params, owner=owner) - except NameError: - if format == _lazy_annotationlib.Format.FORWARDREF: - return forward_ref - else: - raise - - type_ = _type_check( - value, - "Forward references must evaluate to types.", - is_argument=forward_ref.__forward_is_argument__, - allow_special_forms=forward_ref.__forward_is_class__, - ) + if format is None: + format = _lazy_annotationlib.Format.VALUE + value = forward_ref.evaluate(globals=globals, locals=locals, + type_params=type_params, owner=owner, format=format) + + if (isinstance(value, _lazy_annotationlib.ForwardRef) + and format == _lazy_annotationlib.Format.FORWARDREF): + return value + + if isinstance(value, str): + value = _make_forward_ref(value, module=forward_ref.__forward_module__, + owner=owner or forward_ref.__owner__, + is_argument=forward_ref.__forward_is_argument__, + is_class=forward_ref.__forward_is_class__) + if owner is None: + owner = forward_ref.__owner__ return _eval_type( - type_, + value, globals, locals, type_params, @@ -2338,12 +2335,12 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False, # This only affects ForwardRefs. base_globals, base_locals = base_locals, base_globals for name, value in ann.items(): - if value is None: - value = type(None) if isinstance(value, str): value = _make_forward_ref(value, is_argument=False, is_class=True) value = _eval_type(value, base_globals, base_locals, base.__type_params__, format=format, owner=obj) + if value is None: + value = type(None) hints[name] = value if include_extras or format == Format.STRING: return hints @@ -2377,8 +2374,6 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False, localns = globalns type_params = getattr(obj, "__type_params__", ()) for name, value in hints.items(): - if value is None: - value = type(None) if isinstance(value, str): # class-level forward refs were handled above, this must be either # a module-level annotation or a function argument annotation @@ -2387,7 +2382,10 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False, is_argument=not isinstance(obj, types.ModuleType), is_class=False, ) - hints[name] = _eval_type(value, globalns, localns, type_params, format=format, owner=obj) + value = _eval_type(value, globalns, localns, type_params, format=format, owner=obj) + if value is None: + value = type(None) + hints[name] = value return hints if include_extras else {k: _strip_annotations(t) for k, t in hints.items()} diff --git a/Misc/NEWS.d/next/Library/2025-05-12-20-38-57.gh-issue-133960.Aee79f.rst b/Misc/NEWS.d/next/Library/2025-05-12-20-38-57.gh-issue-133960.Aee79f.rst new file mode 100644 index 00000000000000..66e8483b25bc37 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-05-12-20-38-57.gh-issue-133960.Aee79f.rst @@ -0,0 +1,3 @@ +Simplify and improve :func:`typing.evaluate_forward_ref`. It now no longer +raises errors on certain invalid types. In several situations, it is now +able to evaluate forward references that were previously unsupported.