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,
diff --git a/Misc/NEWS.d/next/Core and Builtins/2021-04-25-22-50-47.bpo-43901.oKjG5E.rst b/Misc/NEWS.d/next/Core and Builtins/2021-04-25-22-50-47.bpo-43901.oKjG5E.rst
new file mode 100644
index 0000000..2ab93d1
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2021-04-25-22-50-47.bpo-43901.oKjG5E.rst
@@ -0,0 +1,3 @@
+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/Objects/moduleobject.c b/Objects/moduleobject.c
index a6eb85b..cdb365d 100644
--- a/Objects/moduleobject.c
+++ b/Objects/moduleobject.c
@@ -12,6 +12,9 @@ static Py_ssize_t max_module_number;
_Py_IDENTIFIER(__doc__);
_Py_IDENTIFIER(__name__);
_Py_IDENTIFIER(__spec__);
+_Py_IDENTIFIER(__dict__);
+_Py_IDENTIFIER(__dir__);
+_Py_IDENTIFIER(__annotations__);
static PyMemberDef module_members[] = {
{"__dict__", T_OBJECT, offsetof(PyModuleObject, md_dict), READONLY},
@@ -807,8 +810,6 @@ module_clear(PyModuleObject *m)
static PyObject *
module_dir(PyObject *self, PyObject *args)
{
- _Py_IDENTIFIER(__dict__);
- _Py_IDENTIFIER(__dir__);
PyObject *result = NULL;
PyObject *dict = _PyObject_GetAttrId(self, &PyId___dict__);
@@ -841,6 +842,71 @@ static PyMethodDef module_methods[] = {
{0}
};
+static PyObject *
+module_get_annotations(PyModuleObject *m, void *Py_UNUSED(ignored))
+{
+ PyObject *dict = _PyObject_GetAttrId((PyObject *)m, &PyId___dict__);
+
+ if ((dict == NULL) || !PyDict_Check(dict)) {
+ PyErr_Format(PyExc_TypeError, "<module>.__dict__ is not a dictionary");
+ return NULL;
+ }
+
+ PyObject *annotations;
+ /* there's no _PyDict_GetItemId without WithError, so let's LBYL. */
+ if (_PyDict_ContainsId(dict, &PyId___annotations__)) {
+ annotations = _PyDict_GetItemIdWithError(dict, &PyId___annotations__);
+ /*
+ ** _PyDict_GetItemIdWithError could still fail,
+ ** for instance with a well-timed Ctrl-C or a MemoryError.
+ ** so let's be totally safe.
+ */
+ if (annotations) {
+ Py_INCREF(annotations);
+ }
+ } else {
+ annotations = PyDict_New();
+ if (annotations) {
+ int result = _PyDict_SetItemId(dict, &PyId___annotations__, annotations);
+ if (result) {
+ Py_CLEAR(annotations);
+ }
+ }
+ }
+ Py_DECREF(dict);
+ return annotations;
+}
+
+static int
+module_set_annotations(PyModuleObject *m, PyObject *value, void *Py_UNUSED(ignored))
+{
+ PyObject *dict = _PyObject_GetAttrId((PyObject *)m, &PyId___dict__);
+
+ if ((dict == NULL) || !PyDict_Check(dict)) {
+ PyErr_Format(PyExc_TypeError, "<module>.__dict__ is not a dictionary");
+ return -1;
+ }
+
+ if (value != NULL) {
+ /* set */
+ return _PyDict_SetItemId(dict, &PyId___annotations__, value);
+ }
+
+ /* delete */
+ if (!_PyDict_ContainsId(dict, &PyId___annotations__)) {
+ PyErr_Format(PyExc_AttributeError, "__annotations__");
+ return -1;
+ }
+
+ return _PyDict_DelItemId(dict, &PyId___annotations__);
+}
+
+
+static PyGetSetDef module_getsets[] = {
+ {"__annotations__", (getter)module_get_annotations, (setter)module_set_annotations},
+ {NULL}
+};
+
PyTypeObject PyModule_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"module", /* tp_name */
@@ -872,7 +938,7 @@ PyTypeObject PyModule_Type = {
0, /* tp_iternext */
module_methods, /* tp_methods */
module_members, /* tp_members */
- 0, /* tp_getset */
+ module_getsets, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e1c8be4..ac4dc1d 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -52,6 +52,7 @@ typedef struct PySlot_Offset {
/* alphabetical order */
_Py_IDENTIFIER(__abstractmethods__);
+_Py_IDENTIFIER(__annotations__);
_Py_IDENTIFIER(__class__);
_Py_IDENTIFIER(__class_getitem__);
_Py_IDENTIFIER(__classcell__);
@@ -930,6 +931,73 @@ type_set_doc(PyTypeObject *type, PyObject *value, void *context)
return _PyDict_SetItemId(type->tp_dict, &PyId___doc__, value);
}
+static PyObject *
+type_get_annotations(PyTypeObject *type, void *context)
+{
+ if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
+ PyErr_Format(PyExc_AttributeError, "type object '%s' has no attribute '__annotations__'", type->tp_name);
+ return NULL;
+ }
+
+ PyObject *annotations;
+ /* there's no _PyDict_GetItemId without WithError, so let's LBYL. */
+ if (_PyDict_ContainsId(type->tp_dict, &PyId___annotations__)) {
+ annotations = _PyDict_GetItemIdWithError(type->tp_dict, &PyId___annotations__);
+ /*
+ ** _PyDict_GetItemIdWithError could still fail,
+ ** for instance with a well-timed Ctrl-C or a MemoryError.
+ ** so let's be totally safe.
+ */
+ if (annotations) {
+ if (Py_TYPE(annotations)->tp_descr_get) {
+ annotations = Py_TYPE(annotations)->tp_descr_get(annotations, NULL,
+ (PyObject *)type);
+ } else {
+ Py_INCREF(annotations);
+ }
+ }
+ } else {
+ annotations = PyDict_New();
+ if (annotations) {
+ int result = _PyDict_SetItemId(type->tp_dict, &PyId___annotations__, annotations);
+ if (result) {
+ Py_CLEAR(annotations);
+ } else {
+ PyType_Modified(type);
+ }
+ }
+ }
+ return annotations;
+}
+
+static int
+type_set_annotations(PyTypeObject *type, PyObject *value, void *context)
+{
+ if (!(type->tp_flags & Py_TPFLAGS_HEAPTYPE)) {
+ PyErr_Format(PyExc_TypeError, "can't set attributes of built-in/extension type '%s'", type->tp_name);
+ return -1;
+ }
+
+ int result;
+ if (value != NULL) {
+ /* set */
+ result = _PyDict_SetItemId(type->tp_dict, &PyId___annotations__, value);
+ } else {
+ /* delete */
+ if (!_PyDict_ContainsId(type->tp_dict, &PyId___annotations__)) {
+ PyErr_Format(PyExc_AttributeError, "__annotations__");
+ return -1;
+ }
+ result = _PyDict_DelItemId(type->tp_dict, &PyId___annotations__);
+ }
+
+ if (result == 0) {
+ PyType_Modified(type);
+ }
+ return result;
+}
+
+
/*[clinic input]
type.__instancecheck__ -> bool
@@ -973,6 +1041,7 @@ static PyGetSetDef type_getsets[] = {
{"__dict__", (getter)type_dict, NULL, NULL},
{"__doc__", (getter)type_get_doc, (setter)type_set_doc, NULL},
{"__text_signature__", (getter)type_get_text_signature, NULL, NULL},
+ {"__annotations__", (getter)type_get_annotations, (setter)type_set_annotations, NULL},
{0}
};