It's a fact: for binary operators, *under certain circumstances*,
__rop__ now takes precendence over __op__. Those circumstances are:
- Both arguments are new-style classes
- Both arguments are new-style numbers
- Their implementation slots for tp_op differ
- Their types differ
- The right argument's type is a subtype of the left argument's type
Also did this for the ternary operator (pow) -- only the binary case
is dealt with properly though, since __rpow__ is not supported anyway.
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
index 2c5e7a4..22ae09a 100644
--- a/Lib/test/test_descr.py
+++ b/Lib/test/test_descr.py
@@ -1,8 +1,12 @@
-# Test descriptor-related enhancements
+# Test enhancements related to descriptors and new-style classes
from test_support import verify, verbose, TestFailed, TESTFN
from copy import deepcopy
+def vereq(a, b):
+ if a != b:
+ raise TestFailed, "%r != %r" % (a, b)
+
def testunop(a, res, expr="len(a)", meth="__len__"):
if verbose: print "checking", expr
dict = {'a': a}
@@ -2133,6 +2137,36 @@
a.bar.append(4)
verify(d.bar == [1,2,3])
+def binopoverride():
+ if verbose: print "Testing overrides of binary operations..."
+ class I(int):
+ def __repr__(self):
+ return "I(%r)" % int(self)
+ def __add__(self, other):
+ return I(int(self) + int(other))
+ __radd__ = __add__
+ def __pow__(self, other, mod=None):
+ if mod is None:
+ return I(pow(int(self), int(other)))
+ else:
+ return I(pow(int(self), int(other), int(mod)))
+ def __rpow__(self, other, mod=None):
+ if mod is None:
+ return I(pow(int(other), int(self), mod))
+ else:
+ return I(pow(int(other), int(self), int(mod)))
+
+ vereq(`I(1) + I(2)`, "I(3)")
+ vereq(`I(1) + 2`, "I(3)")
+ vereq(`1 + I(2)`, "I(3)")
+ vereq(`I(2) ** I(3)`, "I(8)")
+ vereq(`2 ** I(3)`, "I(8)")
+ vereq(`I(2) ** 3`, "I(8)")
+ vereq(`pow(I(2), I(3), I(5))`, "I(3)")
+ class S(str):
+ def __eq__(self, other):
+ return self.lower() == other.lower()
+
def test_main():
lists()
@@ -2178,6 +2212,7 @@
setclass()
pickles()
copies()
+ binopoverride()
if verbose: print "All OK"
if __name__ == "__main__":
diff --git a/Objects/abstract.c b/Objects/abstract.c
index fdf1a44..c353159 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -300,11 +300,14 @@
v w Action
-------------------------------------------------------------------
- new new v.op(v,w), w.op(v,w)
+ new new w.op(v,w)[*], v.op(v,w), w.op(v,w)
new old v.op(v,w), coerce(v,w), v.op(v,w)
old new w.op(v,w), coerce(v,w), v.op(v,w)
old old coerce(v,w), v.op(v,w)
+ [*] only when v->ob_type != w->ob_type && w->ob_type is a subclass of
+ v->ob_type
+
Legend:
-------
* new == new style number
@@ -318,29 +321,35 @@
binary_op1(PyObject *v, PyObject *w, const int op_slot)
{
PyObject *x;
- binaryfunc *slot;
- if (v->ob_type->tp_as_number != NULL && NEW_STYLE_NUMBER(v)) {
- slot = NB_BINOP(v->ob_type->tp_as_number, op_slot);
- if (*slot) {
- x = (*slot)(v, w);
- if (x != Py_NotImplemented) {
- return x;
- }
- Py_DECREF(x); /* can't do it */
- }
- if (v->ob_type == w->ob_type) {
- goto binop_error;
- }
+ binaryfunc slotv = NULL;
+ binaryfunc slotw = NULL;
+
+ if (v->ob_type->tp_as_number != NULL && NEW_STYLE_NUMBER(v))
+ slotv = *NB_BINOP(v->ob_type->tp_as_number, op_slot);
+ if (w->ob_type != v->ob_type &&
+ w->ob_type->tp_as_number != NULL && NEW_STYLE_NUMBER(w)) {
+ slotw = *NB_BINOP(w->ob_type->tp_as_number, op_slot);
+ if (slotw == slotv)
+ slotw = NULL;
}
- if (w->ob_type->tp_as_number != NULL && NEW_STYLE_NUMBER(w)) {
- slot = NB_BINOP(w->ob_type->tp_as_number, op_slot);
- if (*slot) {
- x = (*slot)(v, w);
- if (x != Py_NotImplemented) {
- return x;
- }
- Py_DECREF(x); /* can't do it */
- }
+ if (slotw && PyType_IsSubtype(w->ob_type, v->ob_type)) {
+ x = slotw(v, w);
+ if (x != Py_NotImplemented)
+ return x;
+ Py_DECREF(x); /* can't do it */
+ slotw = NULL;
+ }
+ if (slotv) {
+ x = slotv(v, w);
+ if (x != Py_NotImplemented)
+ return x;
+ Py_DECREF(x); /* can't do it */
+ }
+ if (slotw) {
+ x = slotw(v, w);
+ if (x != Py_NotImplemented)
+ return x;
+ Py_DECREF(x); /* can't do it */
}
if (!NEW_STYLE_NUMBER(v) || !NEW_STYLE_NUMBER(w)) {
int err = PyNumber_CoerceEx(&v, &w);
@@ -350,9 +359,10 @@
if (err == 0) {
PyNumberMethods *mv = v->ob_type->tp_as_number;
if (mv) {
- slot = NB_BINOP(mv, op_slot);
- if (*slot) {
- PyObject *x = (*slot)(v, w);
+ binaryfunc slot;
+ slot = *NB_BINOP(mv, op_slot);
+ if (slot) {
+ PyObject *x = slot(v, w);
Py_DECREF(v);
Py_DECREF(w);
return x;
@@ -363,7 +373,6 @@
Py_DECREF(w);
}
}
-binop_error:
Py_INCREF(Py_NotImplemented);
return Py_NotImplemented;
}
@@ -420,6 +429,18 @@
register ternaryfunc *slot;
mv = v->ob_type->tp_as_number;
+ mw = w->ob_type->tp_as_number;
+ if (v->ob_type != w->ob_type && mw && NEW_STYLE_NUMBER(w)) {
+ slot = NB_TERNOP(mw, op_slot);
+ if (*slot && *slot != *NB_TERNOP(mv, op_slot) &&
+ PyType_IsSubtype(w->ob_type, v->ob_type)) {
+ x = (*slot)(v, w, z);
+ if (x != Py_NotImplemented)
+ return x;
+ /* Can't do it... fall through */
+ Py_DECREF(x);
+ }
+ }
if (mv != NULL && NEW_STYLE_NUMBER(v)) {
/* try v.op(v,w,z) */
slot = NB_TERNOP(mv, op_slot);
@@ -435,7 +456,6 @@
goto ternary_error;
}
}
- mw = w->ob_type->tp_as_number;
if (mw != NULL && NEW_STYLE_NUMBER(w)) {
/* try w.op(v,w,z) */
slot = NB_TERNOP(mw,op_slot);