[Python-checkins] bpo-46032: Check types in singledispatch's register() at declaration time (GH-30050)
serhiy-storchaka
webhook-mailer at python.org
Sat Dec 25 07:16:18 EST 2021
https://github.com/python/cpython/commit/078abb676cf759b1e960f78390b6e80f256f0255
commit: 078abb676cf759b1e960f78390b6e80f256f0255
branch: main
author: Serhiy Storchaka <storchaka at gmail.com>
committer: serhiy-storchaka <storchaka at gmail.com>
date: 2021-12-25T14:16:14+02:00
summary:
bpo-46032: Check types in singledispatch's register() at declaration time (GH-30050)
The registry() method of functools.singledispatch() functions checks now
the first argument or the first parameter annotation and raises a TypeError if it is
not supported. Previously unsupported "types" were ignored (e.g. typing.List[int])
or caused an error at calling time (e.g. list[int]).
files:
A Misc/NEWS.d/next/Library/2021-12-11-15-45-07.bpo-46032.HmciLT.rst
M Lib/functools.py
M Lib/test/test_functools.py
diff --git a/Lib/functools.py b/Lib/functools.py
index ccac6f89996b6..91b678c226966 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -740,6 +740,7 @@ def _compose_mro(cls, types):
# Remove entries which are already present in the __mro__ or unrelated.
def is_related(typ):
return (typ not in bases and hasattr(typ, '__mro__')
+ and not isinstance(typ, GenericAlias)
and issubclass(cls, typ))
types = [n for n in types if is_related(n)]
# Remove entries which are strict bases of other entries (they will end up
@@ -841,9 +842,13 @@ def _is_union_type(cls):
from typing import get_origin, Union
return get_origin(cls) in {Union, types.UnionType}
- def _is_valid_union_type(cls):
+ def _is_valid_dispatch_type(cls):
+ if isinstance(cls, type) and not isinstance(cls, GenericAlias):
+ return True
from typing import get_args
- return _is_union_type(cls) and all(isinstance(arg, type) for arg in get_args(cls))
+ return (_is_union_type(cls) and
+ all(isinstance(arg, type) and not isinstance(arg, GenericAlias)
+ for arg in get_args(cls)))
def register(cls, func=None):
"""generic_func.register(cls, func) -> func
@@ -852,9 +857,15 @@ def register(cls, func=None):
"""
nonlocal cache_token
- if func is None:
- if isinstance(cls, type) or _is_valid_union_type(cls):
+ if _is_valid_dispatch_type(cls):
+ if func is None:
return lambda f: register(cls, f)
+ else:
+ if func is not None:
+ raise TypeError(
+ f"Invalid first argument to `register()`. "
+ f"{cls!r} is not a class or union type."
+ )
ann = getattr(cls, '__annotations__', {})
if not ann:
raise TypeError(
@@ -867,7 +878,7 @@ def register(cls, func=None):
# only import typing if annotation parsing is necessary
from typing import get_type_hints
argname, cls = next(iter(get_type_hints(func).items()))
- if not isinstance(cls, type) and not _is_valid_union_type(cls):
+ if not _is_valid_dispatch_type(cls):
if _is_union_type(cls):
raise TypeError(
f"Invalid annotation for {argname!r}. "
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 755ac038792b7..70ae8e06bb475 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -2722,6 +2722,74 @@ def _(arg: int | float):
self.assertEqual(f(1), "types.UnionType")
self.assertEqual(f(1.0), "types.UnionType")
+ def test_register_genericalias(self):
+ @functools.singledispatch
+ def f(arg):
+ return "default"
+
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(list[int], lambda arg: "types.GenericAlias")
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.List[int], lambda arg: "typing.GenericAlias")
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(list[int] | str, lambda arg: "types.UnionTypes(types.GenericAlias)")
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.List[float] | bytes, lambda arg: "typing.Union[typing.GenericAlias]")
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.Any, lambda arg: "typing.Any")
+
+ self.assertEqual(f([1]), "default")
+ self.assertEqual(f([1.0]), "default")
+ self.assertEqual(f(""), "default")
+ self.assertEqual(f(b""), "default")
+
+ def test_register_genericalias_decorator(self):
+ @functools.singledispatch
+ def f(arg):
+ return "default"
+
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(list[int])
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.List[int])
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(list[int] | str)
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.List[int] | str)
+ with self.assertRaisesRegex(TypeError, "Invalid first argument to "):
+ f.register(typing.Any)
+
+ def test_register_genericalias_annotation(self):
+ @functools.singledispatch
+ def f(arg):
+ return "default"
+
+ with self.assertRaisesRegex(TypeError, "Invalid annotation for 'arg'"):
+ @f.register
+ def _(arg: list[int]):
+ return "types.GenericAlias"
+ with self.assertRaisesRegex(TypeError, "Invalid annotation for 'arg'"):
+ @f.register
+ def _(arg: typing.List[float]):
+ return "typing.GenericAlias"
+ with self.assertRaisesRegex(TypeError, "Invalid annotation for 'arg'"):
+ @f.register
+ def _(arg: list[int] | str):
+ return "types.UnionType(types.GenericAlias)"
+ with self.assertRaisesRegex(TypeError, "Invalid annotation for 'arg'"):
+ @f.register
+ def _(arg: typing.List[float] | bytes):
+ return "typing.Union[typing.GenericAlias]"
+ with self.assertRaisesRegex(TypeError, "Invalid annotation for 'arg'"):
+ @f.register
+ def _(arg: typing.Any):
+ return "typing.Any"
+
+ self.assertEqual(f([1]), "default")
+ self.assertEqual(f([1.0]), "default")
+ self.assertEqual(f(""), "default")
+ self.assertEqual(f(b""), "default")
+
class CachedCostItem:
_cost = 1
diff --git a/Misc/NEWS.d/next/Library/2021-12-11-15-45-07.bpo-46032.HmciLT.rst b/Misc/NEWS.d/next/Library/2021-12-11-15-45-07.bpo-46032.HmciLT.rst
new file mode 100644
index 0000000000000..97a553d7ba29f
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-12-11-15-45-07.bpo-46032.HmciLT.rst
@@ -0,0 +1,5 @@
+The ``registry()`` method of :func:`functools.singledispatch` functions
+checks now the first argument or the first parameter annotation and raises a
+TypeError if it is not supported. Previously unsupported "types" were
+ignored (e.g. ``typing.List[int]``) or caused an error at calling time (e.g.
+``list[int]``).
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