Core Python Programming (2nd Edition)

Test Function
The one last thing we want to do is to add a test function. In fact, we already have one, in the form of
the main() function. Now, it is potentially dangerous to have a main() function in our code because there
should only be one main() in the system. We remove this danger by changing the name of our main() to
test() and wrapping it, adding Extest_test() and updating the ExtestMethods array so that they both
look like this:
static PyObject *
Extest_test(PyObject *self, PyObject *args) {
test();
return (PyObject*)Py_BuildValue("");
}
static PyMethodDef
ExtestMethods[] = {
{ "fac", Extest_fac, METH_VARARGS },
{ "doppel", Extest_doppel, METH_VARARGS },
{ "test", Extest_test, METH_VARARGS },
{ NULL, NULL },
};
The Extest_test() module function just runs test() and returns an empty string, resulting in a Python
value of None being returned to the caller.
Now we can run the same test from Python:
>>> Extest.test()
4! == 24
8! == 40320
12! == 479001600
reversing 'abcdef', we get 'fedcba'
reversing 'madam', we get 'madam'
>>>
In Example 22.3, we present the final version of Extest2.c that was used to generate the output we just
witnessed.
Example 22.3. Python-Wrapped Version of C Library (Extest2.c)