Hopefully fix 3-way comparisons. This unfortunately adds yet another
hack, and it's even more disgusting than a PyInstance_Check() call.
If the tp_compare slot is the slot used for overrides in Python,
it's always called.
Add some tests that show what should work too.
diff --git a/Include/object.h b/Include/object.h
index d9c3514..160331e 100644
--- a/Include/object.h
+++ b/Include/object.h
@@ -346,6 +346,10 @@
extern DL_IMPORT(void) (*PyObject_ClearWeakRefs)(PyObject *);
+/* A slot function whose address we need to compare */
+extern int _PyObject_SlotCompare(PyObject *, PyObject *);
+
+
/* PyObject_Dir(obj) acts like Python __builtin__.dir(obj), returning a
list of strings. PyObject_Dir(NULL) is like __builtin__.dir(),
returning the names of the current locals. In this case, if there are
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index fc00318..bd04605 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1831,6 +1831,33 @@
verify(cistr('ONe') in d)
verify(d.get(cistr('thrEE')) == 3)
+def classic_comparisons():
+ if verbose: print "Testing classic comparisons..."
+ for base in (int, object):
+ if verbose: print " (base = %s)" % base
+ class C(base):
+ def __init__(self, value):
+ self.value = int(value)
+ def __cmp__(self, other):
+ if isinstance(other, C):
+ return cmp(self.value, other.value)
+ if isinstance(other, int) or isinstance(other, long):
+ return cmp(self.value, other)
+ return NotImplemented
+ c1 = C(1)
+ c2 = C(2)
+ c3 = C(3)
+ verify(c1 == 1)
+ c = {1: c1, 2: c2, 3: c3}
+ for x in 1, 2, 3:
+ for y in 1, 2, 3:
+ verify(cmp(c[x], c[y]) == cmp(x, y), "x=%d, y=%d" % (x, y))
+ for op in "<", "<=", "==", "!=", ">", ">=":
+ verify(eval("c[x] %s c[y]" % op) == eval("x %s y" % op),
+ "x=%d, y=%d" % (x, y))
+ verify(cmp(c[x], y) == cmp(x, y), "x=%d, y=%d" % (x, y))
+ verify(cmp(x, c[y]) == cmp(x, y), "x=%d, y=%d" % (x, y))
+
def all():
lists()
@@ -1869,6 +1896,7 @@
keywords()
restricted()
str_subclass_as_dict_key()
+ classic_comparisons()
all()
diff --git a/Objects/object.c b/Objects/object.c
index c56c3be..668bd4f 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -455,11 +455,25 @@
/* Comparisons involving instances are given to instance_compare,
which has the same return conventions as this function. */
+ f = v->ob_type->tp_compare;
if (PyInstance_Check(v))
- return (*v->ob_type->tp_compare)(v, w);
+ return (*f)(v, w);
if (PyInstance_Check(w))
return (*w->ob_type->tp_compare)(v, w);
+ /* If both have the same (non-NULL) tp_compare, use it. */
+ if (f != NULL && f == w->ob_type->tp_compare) {
+ c = (*f)(v, w);
+ if (c < 0 && PyErr_Occurred())
+ return -1;
+ return c < 0 ? -1 : c > 0 ? 1 : 0;
+ }
+
+ /* If either tp_compare is _PyObject_SlotCompare, that's safe. */
+ if (f == _PyObject_SlotCompare ||
+ w->ob_type->tp_compare == _PyObject_SlotCompare)
+ return _PyObject_SlotCompare(v, w);
+
/* Try coercion; if it fails, give up */
c = PyNumber_CoerceEx(&v, &w);
if (c < 0)
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 792a9f3..26ddabe 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2761,17 +2761,18 @@
return 2;
}
-static int
-slot_tp_compare(PyObject *self, PyObject *other)
+/* This slot is published for the benefit of try_3way_compare in object.c */
+int
+_PyObject_SlotCompare(PyObject *self, PyObject *other)
{
int c;
- if (self->ob_type->tp_compare == slot_tp_compare) {
+ if (self->ob_type->tp_compare == _PyObject_SlotCompare) {
c = half_compare(self, other);
if (c <= 1)
return c;
}
- if (other->ob_type->tp_compare == slot_tp_compare) {
+ if (other->ob_type->tp_compare == _PyObject_SlotCompare) {
c = half_compare(other, self);
if (c < -1)
return -2;
@@ -3190,7 +3191,7 @@
PyDict_GetItemString(dict, "__repr__"))
type->tp_print = NULL;
- TPSLOT("__cmp__", tp_compare, slot_tp_compare);
+ TPSLOT("__cmp__", tp_compare, _PyObject_SlotCompare);
TPSLOT("__repr__", tp_repr, slot_tp_repr);
TPSLOT("__hash__", tp_hash, slot_tp_hash);
TPSLOT("__call__", tp_call, slot_tp_call);