Commit d8392f1b authored by Guido van Rossum's avatar Guido van Rossum

Patch #1549 by Thomas Herve.

This changes the rules for when __hash__ is inherited slightly,
by allowing it to be inherited when one or more of __lt__, __le__,
__gt__, __ge__ are overridden, as long as __eq__ and __ne__ aren't.
parent f497c472
......@@ -85,6 +85,35 @@ class Vector:
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__),
......@@ -330,8 +359,39 @@ class ListTest(unittest.TestCase):
for op in opmap["lt"]:
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, e:
self.assertEquals(str(e),
"unhashable type: 'DumbEqualityWithoutHash'")
else:
raise test_support.TestFailed("Should not be here")
def test_main():
test_support.run_unittest(VectorTest, NumberTest, MiscTest, DictTest, ListTest)
test_support.run_unittest(VectorTest, NumberTest, MiscTest, DictTest, ListTest, HashableTest)
if __name__ == "__main__":
test_main()
......@@ -3230,28 +3230,22 @@ inherit_special(PyTypeObject *type, PyTypeObject *base)
type->tp_flags |= Py_TPFLAGS_DICT_SUBCLASS;
}
/* Map rich comparison operators to their __xx__ namesakes */
static char *name_op[] = {
"__lt__",
"__le__",
"__eq__",
"__ne__",
"__gt__",
"__ge__",
"__cmp__",
/* These are only for overrides_hash(): */
"__hash__",
static char *hash_name_op[] = {
"__eq__",
"__cmp__",
"__hash__",
NULL
};
static int
overrides_hash(PyTypeObject *type)
{
int i;
char **p;
PyObject *dict = type->tp_dict;
assert(dict != NULL);
for (i = 0; i < 8; i++) {
if (PyDict_GetItemString(dict, name_op[i]) != NULL)
for (p = hash_name_op; *p; p++) {
if (PyDict_GetItemString(dict, *p) != NULL)
return 1;
}
return 0;
......@@ -4846,7 +4840,7 @@ slot_tp_hash(PyObject *self)
func = lookup_method(self, "__hash__", &hash_str);
if (func != NULL) {
if (func != NULL && func != Py_None) {
PyObject *res = PyEval_CallObject(func, NULL);
Py_DECREF(func);
if (res == NULL)
......@@ -4971,6 +4965,15 @@ slot_tp_setattro(PyObject *self, PyObject *name, PyObject *value)
return 0;
}
static char *name_op[] = {
"__lt__",
"__le__",
"__eq__",
"__ne__",
"__gt__",
"__ge__",
};
static PyObject *
half_richcompare(PyObject *self, PyObject *other, int op)
{
......
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