Editing Advanced Scripting (section)

==== Unpacking the Data ====
Let's unpack the data in '''args'''.  Remember, '''args''' has a Python [http://docs.python.org/lib/typesseq.html list of lists].  So, to unpack that we do the following inside of funName:

<source lang="c">
static PyObject*
funName_funName(PyObject* self, PyObject* args)
{
       PyObject *listA, *listB;

       if ( ! PyArg_ParseTuple(args, "(OO)", &listA, &listB) ) {
                printf("Could not unparse objects\n");
                return NULL;
        }

        // let Python know we made two lists
        Py_INCREF(listA);
        Py_INCREF(listB);
 ... more code ...
</source>

Line 4 creates the two C objects that we will unpack the lists into.  They are pointers to PyObjects.
Line 6 is where the magic happens.  We call, '''[http://docs.python.org/api/arg-parsing.html PyArg_ParseTuple]''' passing it the args we got from Python.  The '''(OO)''' is Python's code for ''I'm expecting two <u>O</u>bjects inside a list <u>()</u>''.  Were it three objects, then '''(OOO)'''.  The first object will be put into '''&listA''' and the second into '''&listB'''.  The exact [http://docs.python.org/api/arg-parsing.html argument building specifications] are very useful.