bpo-43901: Lazy-create an empty annotations dict in all unannotated user classes and modules (#25623)
Change class and module objects to lazy-create empty annotations dicts on demand. The annotations dicts are stored in the object's `__dict__` for backwards compatibility.
diff --git a/Lib/test/ann_module4.py b/Lib/test/ann_module4.py
new file mode 100644
index 0000000..13e9aee
--- /dev/null
+++ b/Lib/test/ann_module4.py
@@ -0,0 +1,5 @@
+# This ann_module isn't for test_typing,
+# it's for test_module
+
+a:int=3
+b:str=4
diff --git a/Lib/test/test_grammar.py b/Lib/test/test_grammar.py
index 6f79e19..46f70e5 100644
--- a/Lib/test/test_grammar.py
+++ b/Lib/test/test_grammar.py
@@ -382,8 +382,7 @@ class CC(metaclass=CMeta):
self.assertEqual(CC.__annotations__['xx'], 'ANNOT')
def test_var_annot_module_semantics(self):
- with self.assertRaises(AttributeError):
- print(test.__annotations__)
+ self.assertEqual(test.__annotations__, {})
self.assertEqual(ann_module.__annotations__,
{1: 2, 'x': int, 'y': str, 'f': typing.Tuple[int, int]})
self.assertEqual(ann_module.M.__annotations__,
diff --git a/Lib/test/test_module.py b/Lib/test/test_module.py
index 1d44563..aa5ee49 100644
--- a/Lib/test/test_module.py
+++ b/Lib/test/test_module.py
@@ -286,6 +286,60 @@ class M(ModuleType):
melon = Descr()
self.assertRaises(RuntimeError, getattr, M("mymod"), "melon")
+ def test_lazy_create_annotations(self):
+ # module objects lazy create their __annotations__ dict on demand.
+ # the annotations dict is stored in module.__dict__.
+ # a freshly created module shouldn't have an annotations dict yet.
+ foo = ModuleType("foo")
+ for i in range(4):
+ self.assertFalse("__annotations__" in foo.__dict__)
+ d = foo.__annotations__
+ self.assertTrue("__annotations__" in foo.__dict__)
+ self.assertEqual(foo.__annotations__, d)
+ self.assertEqual(foo.__dict__['__annotations__'], d)
+ if i % 2:
+ del foo.__annotations__
+ else:
+ del foo.__dict__['__annotations__']
+
+ def test_setting_annotations(self):
+ foo = ModuleType("foo")
+ for i in range(4):
+ self.assertFalse("__annotations__" in foo.__dict__)
+ d = {'a': int}
+ foo.__annotations__ = d
+ self.assertTrue("__annotations__" in foo.__dict__)
+ self.assertEqual(foo.__annotations__, d)
+ self.assertEqual(foo.__dict__['__annotations__'], d)
+ if i % 2:
+ del foo.__annotations__
+ else:
+ del foo.__dict__['__annotations__']
+
+ def test_annotations_getset_raises(self):
+ # module has no dict, all operations fail
+ foo = ModuleType.__new__(ModuleType)
+ with self.assertRaises(TypeError):
+ print(foo.__annotations__)
+ with self.assertRaises(TypeError):
+ foo.__annotations__ = {}
+ with self.assertRaises(TypeError):
+ del foo.__annotations__
+
+ # double delete
+ foo = ModuleType("foo")
+ foo.__annotations__ = {}
+ del foo.__annotations__
+ with self.assertRaises(AttributeError):
+ del foo.__annotations__
+
+ def test_annotations_are_created_correctly(self):
+ from test import ann_module4
+ self.assertTrue("__annotations__" in ann_module4.__dict__)
+ del ann_module4.__annotations__
+ self.assertFalse("__annotations__" in ann_module4.__dict__)
+
+
# frozen and namespace module reprs are tested in importlib.
diff --git a/Lib/test/test_opcodes.py b/Lib/test/test_opcodes.py
index d43a830..e880c3f 100644
--- a/Lib/test/test_opcodes.py
+++ b/Lib/test/test_opcodes.py
@@ -31,10 +31,9 @@ def test_setup_annotations_line(self):
except OSError:
pass
- def test_no_annotations_if_not_needed(self):
+ def test_default_annotations_exist(self):
class C: pass
- with self.assertRaises(AttributeError):
- C.__annotations__
+ self.assertEqual(C.__annotations__, {})
def test_use_existing_annotations(self):
ns = {'__annotations__': {1: 2}}
diff --git a/Lib/test/test_type_annotations.py b/Lib/test/test_type_annotations.py
new file mode 100644
index 0000000..f6c99bd
--- /dev/null
+++ b/Lib/test/test_type_annotations.py
@@ -0,0 +1,103 @@
+import unittest
+
+class TypeAnnotationTests(unittest.TestCase):
+
+ def test_lazy_create_annotations(self):
+ # type objects lazy create their __annotations__ dict on demand.
+ # the annotations dict is stored in type.__dict__.
+ # a freshly created type shouldn't have an annotations dict yet.
+ foo = type("Foo", (), {})
+ for i in range(3):
+ self.assertFalse("__annotations__" in foo.__dict__)
+ d = foo.__annotations__
+ self.assertTrue("__annotations__" in foo.__dict__)
+ self.assertEqual(foo.__annotations__, d)
+ self.assertEqual(foo.__dict__['__annotations__'], d)
+ del foo.__annotations__
+
+ def test_setting_annotations(self):
+ foo = type("Foo", (), {})
+ for i in range(3):
+ self.assertFalse("__annotations__" in foo.__dict__)
+ d = {'a': int}
+ foo.__annotations__ = d
+ self.assertTrue("__annotations__" in foo.__dict__)
+ self.assertEqual(foo.__annotations__, d)
+ self.assertEqual(foo.__dict__['__annotations__'], d)
+ del foo.__annotations__
+
+ def test_annotations_getset_raises(self):
+ # builtin types don't have __annotations__ (yet!)
+ with self.assertRaises(AttributeError):
+ print(float.__annotations__)
+ with self.assertRaises(TypeError):
+ float.__annotations__ = {}
+ with self.assertRaises(TypeError):
+ del float.__annotations__
+
+ # double delete
+ foo = type("Foo", (), {})
+ foo.__annotations__ = {}
+ del foo.__annotations__
+ with self.assertRaises(AttributeError):
+ del foo.__annotations__
+
+ def test_annotations_are_created_correctly(self):
+ class C:
+ a:int=3
+ b:str=4
+ self.assertTrue("__annotations__" in C.__dict__)
+ del C.__annotations__
+ self.assertFalse("__annotations__" in C.__dict__)
+
+ def test_descriptor_still_works(self):
+ class C:
+ def __init__(self, name=None, bases=None, d=None):
+ self.my_annotations = None
+
+ @property
+ def __annotations__(self):
+ if not hasattr(self, 'my_annotations'):
+ self.my_annotations = {}
+ if not isinstance(self.my_annotations, dict):
+ self.my_annotations = {}
+ return self.my_annotations
+
+ @__annotations__.setter
+ def __annotations__(self, value):
+ if not isinstance(value, dict):
+ raise ValueError("can only set __annotations__ to a dict")
+ self.my_annotations = value
+
+ @__annotations__.deleter
+ def __annotations__(self):
+ if hasattr(self, 'my_annotations') and self.my_annotations == None:
+ raise AttributeError('__annotations__')
+ self.my_annotations = None
+
+ c = C()
+ self.assertEqual(c.__annotations__, {})
+ d = {'a':'int'}
+ c.__annotations__ = d
+ self.assertEqual(c.__annotations__, d)
+ with self.assertRaises(ValueError):
+ c.__annotations__ = 123
+ del c.__annotations__
+ with self.assertRaises(AttributeError):
+ del c.__annotations__
+ self.assertEqual(c.__annotations__, {})
+
+
+ class D(metaclass=C):
+ pass
+
+ self.assertEqual(D.__annotations__, {})
+ d = {'a':'int'}
+ D.__annotations__ = d
+ self.assertEqual(D.__annotations__, d)
+ with self.assertRaises(ValueError):
+ D.__annotations__ = 123
+ del D.__annotations__
+ with self.assertRaises(AttributeError):
+ del D.__annotations__
+ self.assertEqual(D.__annotations__, {})
diff --git a/Lib/typing.py b/Lib/typing.py
index d409517..ff96434 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1677,6 +1677,8 @@ def get_type_hints(obj, globalns=None, localns=None, include_extras=False):
else:
base_globals = globalns
ann = base.__dict__.get('__annotations__', {})
+ if isinstance(ann, types.GetSetDescriptorType):
+ ann = {}
base_locals = dict(vars(base)) if localns is None else localns
if localns is None and globalns is None:
# This is surprising, but required. Before Python 3.10,