bpo-41249: Fix postponed annotations for TypedDict (GH-27017) (#27204)
This fixes TypedDict to work with get_type_hints and postponed evaluation of annotations across modules.
This is done by adding the module name to ForwardRef at the time the object is created and using that to resolve the globals during the evaluation.
Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
(cherry picked from commit 889036f7ef7290ef15b6c3373023f6a35387af0c)
Co-authored-by: Germán Méndez Bravo <german.mb@gmail.com>
diff --git a/Lib/typing.py b/Lib/typing.py
index 2caa619..1823cb8 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -134,16 +134,16 @@
# legitimate imports of those modules.
-def _type_convert(arg):
+def _type_convert(arg, module=None):
"""For converting None to type(None), and strings to ForwardRef."""
if arg is None:
return type(None)
if isinstance(arg, str):
- return ForwardRef(arg)
+ return ForwardRef(arg, module=module)
return arg
-def _type_check(arg, msg, is_argument=True):
+def _type_check(arg, msg, is_argument=True, module=None):
"""Check that the argument is a type, and return it (internal helper).
As a special case, accept None and return type(None) instead. Also wrap strings
@@ -159,7 +159,7 @@ def _type_check(arg, msg, is_argument=True):
if is_argument:
invalid_generic_forms = invalid_generic_forms + (ClassVar, Final)
- arg = _type_convert(arg)
+ arg = _type_convert(arg, module=module)
if (isinstance(arg, _GenericAlias) and
arg.__origin__ in invalid_generic_forms):
raise TypeError(f"{arg} is not valid as type argument")
@@ -630,9 +630,9 @@ class ForwardRef(_Final, _root=True):
__slots__ = ('__forward_arg__', '__forward_code__',
'__forward_evaluated__', '__forward_value__',
- '__forward_is_argument__')
+ '__forward_is_argument__', '__forward_module__')
- def __init__(self, arg, is_argument=True):
+ def __init__(self, arg, is_argument=True, module=None):
if not isinstance(arg, str):
raise TypeError(f"Forward reference must be a string -- got {arg!r}")
try:
@@ -644,6 +644,7 @@ def __init__(self, arg, is_argument=True):
self.__forward_evaluated__ = False
self.__forward_value__ = None
self.__forward_is_argument__ = is_argument
+ self.__forward_module__ = module
def _evaluate(self, globalns, localns, recursive_guard):
if self.__forward_arg__ in recursive_guard:
@@ -655,6 +656,10 @@ def _evaluate(self, globalns, localns, recursive_guard):
globalns = localns
elif localns is None:
localns = globalns
+ if self.__forward_module__ is not None:
+ globalns = getattr(
+ sys.modules.get(self.__forward_module__, None), '__dict__', globalns
+ )
type_ =_type_check(
eval(self.__forward_code__, globalns, localns),
"Forward references must evaluate to types.",
@@ -2233,7 +2238,8 @@ def __new__(cls, name, bases, ns, total=True):
own_annotation_keys = set(own_annotations.keys())
msg = "TypedDict('Name', {f0: t0, f1: t1, ...}); each t must be a type"
own_annotations = {
- n: _type_check(tp, msg) for n, tp in own_annotations.items()
+ n: _type_check(tp, msg, module=tp_dict.__module__)
+ for n, tp in own_annotations.items()
}
required_keys = set()
optional_keys = set()