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bpo-46730: Add more info to @property AttributeError messages (GH-31311)

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On `obj.read_only_property = x`, raise `AttributeError: property 'read_only_property' of 'A' object has no setter`.
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Alex-Blade 2022-02-16 10:07:34 +03:00 • committed by GitHub
parent 4d8a515d19
commit 0cb765b2ce
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5 changed files with 40 additions and 22 deletions
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8
Doc/howto/descriptor.rst
View file

@ -991,17 +991,17 @@ here is a pure Python equivalent:
if obj is None:
return self
if self.fget is None:
raise AttributeError(f'unreadable attribute {self._name}')
raise AttributeError(f"property '{self._name}' has no getter")
return self.fget(obj)
def __set__(self, obj, value):
if self.fset is None:
raise AttributeError(f"can't set attribute {self._name}")
raise AttributeError(f"property '{self._name}' has no setter")
self.fset(obj, value)
def __delete__(self, obj):
if self.fdel is None:
raise AttributeError(f"can't delete attribute {self._name}")
raise AttributeError(f"property '{self._name}' has no deleter")
self.fdel(obj)
def getter(self, fget):
@ -1456,7 +1456,7 @@ attributes stored in ``__slots__``:
>>> mark.dept = 'Space Pirate'
Traceback (most recent call last):
...
AttributeError: can't set attribute
AttributeError: property 'dept' of 'Immutable' object has no setter
>>> mark.location = 'Mars'
Traceback (most recent call last):
...

10
Lib/test/test_property.py
View file

@ -322,27 +322,27 @@ class _PropertyUnreachableAttribute:
cls.obj = cls.cls()
def test_get_property(self):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("unreadable attribute")):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("has no getter")):
self.obj.foo
def test_set_property(self):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't set attribute")):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("has no setter")):
self.obj.foo = None
def test_del_property(self):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("can't delete attribute")):
with self.assertRaisesRegex(AttributeError, self._format_exc_msg("has no deleter")):
del self.obj.foo
class PropertyUnreachableAttributeWithName(_PropertyUnreachableAttribute, unittest.TestCase):
msg_format = "^{} 'foo'$"
msg_format = r"^property 'foo' of 'PropertyUnreachableAttributeWithName\.cls' object {}$"
class cls:
foo = property()
class PropertyUnreachableAttributeNoName(_PropertyUnreachableAttribute, unittest.TestCase):
msg_format = "^{}$"
msg_format = "^property of 'PropertyUnreachableAttributeNoName\.cls' object {}$"
class cls:
pass

1
Misc/ACKS
View file

@ -985,6 +985,7 @@ Erno Kuusela
Ross Lagerwall
Cameron Laird
Loïc Lajeanne
Alexander Lakeev
David Lam
Thomas Lamb
Valerie Lambert

3
Misc/NEWS.d/next/Core and Builtins/2022-02-14-21-04-43.bpo-46730.rYJ1w5.rst Normal file
View file

@ -0,0 +1,3 @@
Message of AttributeError caused by getting, setting or deleting a property
without the corresponding function now mentions that the attribute is in fact
a property and also specifies type of the class that it belongs to.

40
Objects/descrobject.c
View file

@ -1463,17 +1463,17 @@ class property(object):
if inst is None:
return self
if self.__get is None:
raise AttributeError, "unreadable attribute"
raise AttributeError, "property has no getter"
return self.__get(inst)
def __set__(self, inst, value):
if self.__set is None:
raise AttributeError, "can't set attribute"
raise AttributeError, "property has no setter"
return self.__set(inst, value)
def __delete__(self, inst):
if self.__del is None:
raise AttributeError, "can't delete attribute"
raise AttributeError, "property has no deleter"
return self.__del(inst)
*/
@ -1586,9 +1586,15 @@ property_descr_get(PyObject *self, PyObject *obj, PyObject *type)
propertyobject *gs = (propertyobject *)self;
if (gs->prop_get == NULL) {
if (gs->prop_name != NULL) {
PyErr_Format(PyExc_AttributeError, "unreadable attribute %R", gs->prop_name);
} else {
PyErr_SetString(PyExc_AttributeError, "unreadable attribute");
PyErr_Format(PyExc_AttributeError,
"property %R of %R object has no getter",
gs->prop_name,
PyType_GetQualName(Py_TYPE(obj)));
}
else {
PyErr_Format(PyExc_AttributeError,
"property of %R object has no getter",
PyType_GetQualName(Py_TYPE(obj)));
}
return NULL;
@ -1611,18 +1617,26 @@ property_descr_set(PyObject *self, PyObject *obj, PyObject *value)
}
if (func == NULL) {
if (gs->prop_name != NULL) {
if (gs->prop_name != NULL && obj != NULL) {
PyErr_Format(PyExc_AttributeError,
value == NULL ?
"can't delete attribute %R" :
"can't set attribute %R",
gs->prop_name);
"property %R of %R object has no deleter" :
"property %R of %R object has no setter",
gs->prop_name,
PyType_GetQualName(Py_TYPE(obj)));
}
else if (obj != NULL) {
PyErr_Format(PyExc_AttributeError,
value == NULL ?
"property of %R object has no deleter" :
"property of %R object has no setter",
PyType_GetQualName(Py_TYPE(obj)));
}
else {
PyErr_SetString(PyExc_AttributeError,
value == NULL ?
"can't delete attribute" :
"can't set attribute");
value == NULL ?
"property has no deleter" :
"property has no setter");
}
return -1;
}