Thomas Herve added the comment:
I gave it a try. The following patch corrects 2 problems:
* classes with only __lt__ and __gt__ defined are hashable
* classes defining __eq__ get a meaningful exception.
I've restricted the hash_name_op to the bare minimum, but no tests
failed, so I supposed it was enough :).
Please review.
Added file: http://bugs.python.org/file8871/1549_1.diff
__________________________________
Tracker <[EMAIL PROTECTED]>
<http://bugs.python.org/issue1549>
__________________________________
Index: Objects/typeobject.c
===================================================================
--- Objects/typeobject.c (revision 59318)
+++ Objects/typeobject.c (working copy)
@@ -3230,14 +3230,8 @@
type->tp_flags |= Py_TPFLAGS_DICT_SUBCLASS;
}
-/* Map rich comparison operators to their __xx__ namesakes */
-static char *name_op[] = {
- "__lt__",
- "__le__",
+static char *hash_name_op[] = {
"__eq__",
- "__ne__",
- "__gt__",
- "__ge__",
"__cmp__",
/* These are only for overrides_hash(): */
"__hash__",
@@ -3246,13 +3240,14 @@
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 +4841,7 @@
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 +4966,15 @@
return 0;
}
+static char *name_op[] = {
+ "__lt__",
+ "__le__",
+ "__eq__",
+ "__ne__",
+ "__gt__",
+ "__ge__",
+};
+
static PyObject *
half_richcompare(PyObject *self, PyObject *other, int op)
{
Index: Lib/test/test_richcmp.py
===================================================================
--- Lib/test/test_richcmp.py (revision 59318)
+++ Lib/test/test_richcmp.py (working copy)
@@ -85,6 +85,35 @@
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 @@
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()
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