Hrvoje Niksic wrote:
PyObject *sum(PyObject *ignored, PyObject *lst) { int i, s = 0; if (!PyList_Check(lst)) { PyErr_Format(PyExc_TypeError, "sum: expected list, got %s", lst->ob_type->tp_name); return NULL; } for (i = 0; i < PyList_GET_SIZE(lst); i++) { ... sum the list ... return PyInt_FromLong(s); }
My question is: which option should I use with PyArg_ParseTuple?
If your function is declared to take one argument with METH_O, you don't need PyArg_ParseTuple at all. If it's declared to take a variable number of arguments, you'd use it like this:
PyObject *sum(PyObject *ignored, PyObject *args) { int i, s = 0; PyObject *lst; if (!PyArg_ParseTuple(args, "O", &lst)) return NULL; ... }
You can also write your code in Cython. The following Cython code will generate roughly the same C code that you present above:
def sum(list l):
cdef int i, s = 0
for i in l:
s += i
return s
Stefan