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gh-119180: Improvements to ForwardRef.evaluate (#122210)

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Noticed some issues while writing documentation for this method.
This commit is contained in:
Jelle Zijlstra 2024-08-11 16:42:57 -07:00 • committed by GitHub
parent a6644d4464
commit 016f4b5975
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GPG key ID: B5690EEEBB952194
3 changed files with 60 additions and 11 deletions
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25
Lib/annotationlib.py
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@ -74,7 +74,7 @@ class ForwardRef:
def evaluate(self, *, globals=None, locals=None, type_params=None, owner=None):
"""Evaluate the forward reference and return the value.
If the forward reference is not evaluatable, raise an exception.
If the forward reference cannot be evaluated, raise an exception.
"""
if self.__forward_evaluated__:
return self.__forward_value__
@ -89,12 +89,10 @@ class ForwardRef:
return value
if owner is None:
owner = self.__owner__
if type_params is None and owner is None:
raise TypeError("Either 'type_params' or 'owner' must be provided")
if self.__forward_module__ is not None:
if globals is None and self.__forward_module__ is not None:
globals = getattr(
sys.modules.get(self.__forward_module__, None), "__dict__", globals
sys.modules.get(self.__forward_module__, None), "__dict__", None
)
if globals is None:
globals = self.__globals__
@ -112,14 +110,14 @@ class ForwardRef:
if locals is None:
locals = {}
if isinstance(self.__owner__, type):
locals.update(vars(self.__owner__))
if isinstance(owner, type):
locals.update(vars(owner))
if type_params is None and self.__owner__ is not None:
if type_params is None and owner is not None:
# "Inject" type parameters into the local namespace
# (unless they are shadowed by assignments *in* the local namespace),
# as a way of emulating annotation scopes when calling `eval()`
type_params = getattr(self.__owner__, "__type_params__", None)
type_params = getattr(owner, "__type_params__", None)
# type parameters require some special handling,
# as they exist in their own scope
@ -129,7 +127,14 @@ class ForwardRef:
# but should in turn be overridden by names in the class scope
# (which here are called `globalns`!)
if type_params is not None:
globals, locals = dict(globals), dict(locals)
if globals is None:
globals = {}
else:
globals = dict(globals)
if locals is None:
locals = {}
else:
locals = dict(locals)
for param in type_params:
param_name = param.__name__
if not self.__forward_is_class__ or param_name not in globals: