Use Argument Clinic

Taken from patch by Sergey B Kirpichev <[email protected]>

Author: sayandipdutta

Modules/_functoolsmodule.c

@@ -932,19 +932,29 @@ _functools_cmp_to_key_impl(PyObject *module, PyObject *mycmp)
 
 /* reduce (used to be a builtin) ********************************************/
 
-// Not converted to argument clinic, because of `args` in-place modification.
-// AC will affect performance.
+/*[clinic input]
+_functools.reduce
+
+    function as func: object
+    iterable as seq: object
+    /
+    initial as result: object(c_default="NULL") = None
+
+Apply a function of two arguments cumulatively.
+
+Apply it to the items of a sequence or iterable, from left to right, so as to
+reduce the iterable to a single value.  For example, reduce(lambda x, y: x+y,
+[1, 2, 3, 4, 5]) calculates ((((1+2)+3)+4)+5).  If initial is present, it is
+placed before the items of the iterable in the calculation, and serves as a
+default when the iterable is empty.
+[clinic start generated code]*/
+
 static PyObject *
-functools_reduce(PyObject *self, PyObject *args, PyObject *kwargs)
+_functools_reduce_impl(PyObject *module, PyObject *func, PyObject *seq,
+                       PyObject *result)
+/*[clinic end generated code: output=30d898fe1267c79d input=b7082b8b1473fdc2]*/
 {
-    PyObject *seq, *func, *result = NULL, *it;
-    static char *keywords[] = {"", "", "initial", NULL};
-
-    if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OO|O:reduce", keywords,
-                                     &func, &seq, &result))
-    {
-        return NULL;
-    }
+    PyObject *args, *it;
 
     if (result != NULL)
         Py_INCREF(result);
@@ -1011,16 +1021,6 @@ functools_reduce(PyObject *self, PyObject *args, PyObject *kwargs)
     return NULL;
 }
 
-PyDoc_STRVAR(functools_reduce_doc,
-"reduce(function, iterable, /[, initial]) -> value\n\
-\n\
-Apply a function of two arguments cumulatively to the items of a sequence\n\
-or iterable, from left to right, so as to reduce the iterable to a single\n\
-value.  For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates\n\
-((((1+2)+3)+4)+5).  If initial is present, it is placed before the items\n\
-of the iterable in the calculation, and serves as a default when the\n\
-iterable is empty.");
-
 /* lru_cache object **********************************************************/
 
 /* There are four principal algorithmic differences from the pure python version:
@@ -1725,8 +1725,7 @@ PyDoc_STRVAR(_functools_doc,
 "Tools that operate on functions.");
 
 static PyMethodDef _functools_methods[] = {
-    {"reduce", _PyCFunction_CAST(functools_reduce), METH_VARARGS|METH_KEYWORDS,
-        functools_reduce_doc},
+    _FUNCTOOLS_REDUCE_METHODDEF
     _FUNCTOOLS_CMP_TO_KEY_METHODDEF
     {NULL,              NULL}           /* sentinel */
 };