PyAPI_FUNC(int) PyObject_GenericSetAttr(PyObject *,
PyObject *, PyObject *);
PyAPI_FUNC(long) PyObject_Hash(PyObject *);
+PyAPI_FUNC(long) PyObject_HashNotImplemented(PyObject *);
PyAPI_FUNC(int) PyObject_IsTrue(PyObject *);
PyAPI_FUNC(int) PyObject_Not(PyObject *);
PyAPI_FUNC(int) PyCallable_Check(PyObject *);
for flag in flags:
self._ignored_flags.remove(flag)
- def __hash__(self):
- """A Context cannot be hashed."""
- # We inherit object.__hash__, so we must deny this explicitly
- raise TypeError("Cannot hash a Context.")
+ # We inherit object.__hash__, so we must deny this explicitly
+ __hash__ = None
def Etiny(self):
"""Returns Etiny (= Emin - prec + 1)"""
# So instances of AllEq must be found in all non-empty sequences.
def __eq__(self, other):
return True
- def __hash__(self):
- raise NotImplemented
+ __hash__ = None # Can't meet hash invariant requirements
self.assert_(AllEq() not in self.type2test([]))
self.assert_(AllEq() in self.type2test([1]))
self.assertEqual(hash(d), 144)
D.__hash__ = lambda self: 100
self.assertEqual(hash(d), 100)
+ D.__hash__ = None
+ self.assertRaises(TypeError, hash, d)
del D.__hash__
self.assertEqual(hash(d), 144)
+ B.__hash__ = None
+ self.assertRaises(TypeError, hash, d)
del B.__hash__
self.assertEqual(hash(d), 314)
+ C.__hash__ = None
+ self.assertRaises(TypeError, hash, d)
del C.__hash__
self.assertEqual(hash(d), 42)
+ A.__hash__ = None
+ self.assertRaises(TypeError, hash, d)
del A.__hash__
self.assertEqual(hash(d), orig_hash)
d.foo = 42
# test the invariant that
# iff a==b then hash(a)==hash(b)
#
+# Also test that hash implementations are inherited as expected
import unittest
from test import support
+from collections import Hashable
class HashEqualityTestCase(unittest.TestCase):
self.same_hash(float(0.5), complex(0.5, 0.0))
+_default_hash = object.__hash__
+class DefaultHash(object): pass
+
+_FIXED_HASH_VALUE = 42
+class FixedHash(object):
+ def __hash__(self):
+ return _FIXED_HASH_VALUE
+
+class OnlyEquality(object):
+ def __eq__(self, other):
+ return self is other
+
+class OnlyInequality(object):
+ def __ne__(self, other):
+ return self is not other
+
+class OnlyCmp(object):
+ def __cmp__(self, other):
+ return cmp(id(self), id(other))
+
+class InheritedHashWithEquality(FixedHash, OnlyEquality): pass
+class InheritedHashWithInequality(FixedHash, OnlyInequality): pass
+class InheritedHashWithCmp(FixedHash, OnlyCmp): pass
+
+class NoHash(object):
+ __hash__ = None
+
+class HashInheritanceTestCase(unittest.TestCase):
+ default_expected = [object(),
+ DefaultHash(),
+ OnlyInequality(),
+ ]
+ fixed_expected = [FixedHash(),
+ InheritedHashWithEquality(),
+ InheritedHashWithInequality(),
+ InheritedHashWithCmp(),
+ ]
+ error_expected = [NoHash(),
+ OnlyEquality(),
+ OnlyCmp(),
+ ]
+
+ def test_default_hash(self):
+ for obj in self.default_expected:
+ self.assertEqual(hash(obj), _default_hash(obj))
+
+ def test_fixed_hash(self):
+ for obj in self.fixed_expected:
+ self.assertEqual(hash(obj), _FIXED_HASH_VALUE)
+
+ def test_error_hash(self):
+ for obj in self.error_expected:
+ self.assertRaises(TypeError, hash, obj)
+
+ def test_hashable(self):
+ objects = (self.default_expected +
+ self.fixed_expected)
+ for obj in objects:
+ self.assert_(isinstance(obj, Hashable), repr(obj))
+
+ def test_not_hashable(self):
+ for obj in self.error_expected:
+ self.assertFalse(isinstance(obj, Hashable), repr(obj))
+
+
def test_main():
- support.run_unittest(HashEqualityTestCase)
+ support.run_unittest(HashEqualityTestCase,
+ HashInheritanceTestCase)
if __name__ == "__main__":
def __setitem__(self, i, v):
self.data[i] = v
- def __hash__(self):
- raise TypeError("Vectors cannot be hashed")
+ __hash__ = None # Vectors cannot be hashed
def __bool__(self):
raise TypeError("Vectors cannot be used in Boolean contexts")
raise ValueError("Cannot compare vectors of different length")
return other
-
-class SimpleOrder(object):
- """
- A simple class that defines order but not full comparison.
- """
-
- def __init__(self, value):
- self.value = value
-
- def __lt__(self, other):
- if not isinstance(other, SimpleOrder):
- return True
- return self.value < other.value
-
- def __gt__(self, other):
- if not isinstance(other, SimpleOrder):
- return False
- return self.value > other.value
-
-
-class DumbEqualityWithoutHash(object):
- """
- A class that define __eq__, but no __hash__: it shouldn't be hashable.
- """
-
- def __eq__(self, other):
- return False
-
-
opmap = {
"lt": (lambda a,b: a< b, operator.lt, operator.__lt__),
"le": (lambda a,b: a<=b, operator.le, operator.__le__),
self.assertIs(op(x, y), True)
-class HashableTest(unittest.TestCase):
- """
- Test hashability of classes with rich operators defined.
- """
-
- def test_simpleOrderHashable(self):
- """
- A class that only defines __gt__ and/or __lt__ should be hashable.
- """
- a = SimpleOrder(1)
- b = SimpleOrder(2)
- self.assert_(a < b)
- self.assert_(b > a)
- self.assert_(a.__hash__ is not None)
-
- def test_notHashableException(self):
- """
- If a class is not hashable, it should raise a TypeError with an
- understandable message.
- """
- a = DumbEqualityWithoutHash()
- try:
- hash(a)
- except TypeError as e:
- self.assertEquals(str(e),
- "unhashable type: 'DumbEqualityWithoutHash'")
- else:
- raise support.TestFailed("Should not be here")
-
-
def test_main():
- support.run_unittest(VectorTest, NumberTest, MiscTest, DictTest, ListTest, HashableTest)
+ support.run_unittest(VectorTest, NumberTest, MiscTest, DictTest, ListTest)
if __name__ == "__main__":
test_main()
return 0;
}
-static long
-deque_nohash(PyObject *self)
-{
- PyErr_SetString(PyExc_TypeError, "deque objects are unhashable");
- return -1;
-}
-
static PyObject *
deque_copy(PyObject *deque)
{
0, /* tp_as_number */
&deque_as_sequence, /* tp_as_sequence */
0, /* tp_as_mapping */
- deque_nohash, /* tp_hash */
+ (hashfunc)PyObject_HashNotImplemented, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_as_number */
&dict_as_sequence, /* tp_as_sequence */
&dict_as_mapping, /* tp_as_mapping */
- 0, /* tp_hash */
+ (hashfunc)PyObject_HashNotImplemented, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_as_number */
&list_as_sequence, /* tp_as_sequence */
&list_as_mapping, /* tp_as_mapping */
- 0, /* tp_hash */
+ (hashfunc)PyObject_HashNotImplemented, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
#endif
}
+long
+PyObject_HashNotImplemented(PyObject *v)
+{
+ PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
+ Py_TYPE(v)->tp_name);
+ return -1;
+}
long
PyObject_Hash(PyObject *v)
{
- PyTypeObject *tp = v->ob_type;
+ PyTypeObject *tp = Py_TYPE(v);
if (tp->tp_hash != NULL)
return (*tp->tp_hash)(v);
/* Otherwise, the object can't be hashed */
- PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
- v->ob_type->tp_name);
- return -1;
+ return PyObject_HashNotImplemented(v);
}
PyObject *
&set_as_number, /* tp_as_number */
&set_as_sequence, /* tp_as_sequence */
0, /* tp_as_mapping */
- 0, /* tp_hash */
+ (hashfunc)PyObject_HashNotImplemented, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
/* Hack for tp_hash and __hash__.
If after all that, tp_hash is still NULL, and __hash__ is not in
- tp_dict, set tp_dict['__hash__'] equal to None.
+ tp_dict, set tp_hash to PyObject_HashNotImplemented and
+ tp_dict['__hash__'] equal to None.
This signals that __hash__ is not inherited.
*/
if (type->tp_hash == NULL) {
if (PyDict_GetItemString(type->tp_dict, "__hash__") == NULL) {
if (PyDict_SetItemString(type->tp_dict, "__hash__", Py_None) < 0)
goto error;
+ type->tp_hash = PyObject_HashNotImplemented;
}
}
}
if (func == NULL) {
- PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
- Py_TYPE(self)->tp_name);
- return -1;
+ return PyObject_HashNotImplemented(self);
}
res = PyEval_CallObject(func, NULL);
sanity checks. I'll buy the first person to
point out a bug in this reasoning a beer. */
}
+ else if (descr == Py_None &&
+ strcmp(p->name, "__hash__") == 0) {
+ /* We specifically allow __hash__ to be set to None
+ to prevent inheritance of the default
+ implementation from object.__hash__ */
+ specific = PyObject_HashNotImplemented;
+ }
else {
use_generic = 1;
generic = p->function;
continue;
if (PyDict_GetItem(dict, p->name_strobj))
continue;
- descr = PyDescr_NewWrapper(type, p, *ptr);
- if (descr == NULL)
- return -1;
- if (PyDict_SetItem(dict, p->name_strobj, descr) < 0)
- return -1;
- Py_DECREF(descr);
+ if (*ptr == PyObject_HashNotImplemented) {
+ /* Classes may prevent the inheritance of the tp_hash
+ slot by storing PyObject_HashNotImplemented in it. Make it
+ visible as a None value for the __hash__ attribute. */
+ if (PyDict_SetItem(dict, p->name_strobj, Py_None) < 0)
+ return -1;
+ }
+ else {
+ descr = PyDescr_NewWrapper(type, p, *ptr);
+ if (descr == NULL)
+ return -1;
+ if (PyDict_SetItem(dict, p->name_strobj, descr) < 0)
+ return -1;
+ Py_DECREF(descr);
+ }
}
if (type->tp_new != NULL) {
if (add_tp_new_wrapper(type) < 0)
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