How to call a python function in C++

[clio]

Hi,
Here is a very confusing problem. I am trying to call a python function 
in C. I build a .cxx which have following functions:

......
static PyObject *my_callback=NULL;

static PyObject * my_set_callback(PyObject * dummy,PyObject * args)
  {
            PyObject *result = NULL;
            PyObject *temp;

            if (PyArg_ParseTuple(args, "O:set_callback", &temp)) {
                if (!PyCallable_Check(temp)) {
                    PyErr_SetString(PyExc_TypeError, "parameter must be 
callable");
                    return NULL;
                }
                Py_XINCREF(temp);         /* Add a reference to new 
callback */
                Py_XDECREF(my_callback);  /* Dispose of previous callback */
                my_callback = temp;       /* Remember new callback */
                /* Boilerplate to return "None" */
                Py_INCREF(Py_None);
                result = Py_None;
            }
            return result;
        }
..........
Acctually, this code is from online manual. Then in another c++ program 
I have this:

extern PyObject *my_callback;
......
PyObject * arglist;
arglist = Py_BuildValue("(s1000)", buf);
PyObject *result;

result = PyEval_CallObject(my_callback, arglist);
Py_DECREF(arglist);

.......

I compiled them to seprate object file and link them to be provapimodule.so.

I got no error in compiling, but when I load the provapi in python, 
there is an error:

 >ImportError: ./provapimodule.so: undefined symbol: my_callback.

Then I try to remove "static" in defination of my_callback. This time, I 
can load the module without error, and I can access provapi.my_callback 
too. But I met this:

 >>> provapi.my_set_callback(binstr,happy)
Traceback (innermost last):
   File "<stdin>", line 1, in ?
AttributeError: my_set_callback

I do not know what does this mean?

I am using g++ (gcc version 2.96 20000731) and Linux 7.1. Python 1.5.2.

Anyone can help me, thank you!

clio