Implement the round functionality for PEP 3141, and add tests for it.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 2c163a1..b55dd51 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -1378,10 +1378,34 @@
int ndigits = 0;
int i;
static char *kwlist[] = {"number", "ndigits", 0};
+ PyObject* real;
- if (!PyArg_ParseTupleAndKeywords(args, kwds, "d|i:round",
- kwlist, &number, &ndigits))
+ if (!PyArg_ParseTupleAndKeywords(args, kwds, "O|i:round",
+ kwlist, &real, &ndigits))
return NULL;
+
+ if (ndigits == 0) {
+ PyObject *res;
+ PyObject *d = PyObject_GetAttrString(real, "__round__");
+ if (d == NULL && !PyFloat_Check(real)) {
+ PyErr_SetString(PyExc_TypeError,
+ "round() argument must have __round__ attribute or be a float");
+ return NULL;
+ }
+ if (d == NULL) {
+ PyErr_Clear();
+ } else {
+ res = PyObject_CallFunction(d, "");
+ Py_DECREF(d);
+ return res;
+ }
+ } else if (!PyFloat_Check(real)) {
+ PyErr_SetString(PyExc_TypeError,
+ "round() argument must have __round__ attribute or be a float");
+ return NULL;
+ }
+
+ number = PyFloat_AsDouble(real);
f = 1.0;
i = abs(ndigits);
while (--i >= 0)