#include <Python.h>
#include <stdlib.h>

/***********************************************/
/* 1) code to route events to Python object    */
/* note that we could run strings here instead */
/***********************************************/

static PyObject *Handler = NULL;     /* keep Python object in C */

void Route_Event(char *label, int count) 
{
    char *cres;
    PyObject *args, *pres;

    /* call Python handler */
    args = Py_BuildValue("(si)", label, count);   /* make arg-list */
    pres = PyEval_CallObject(Handler, args);      /* apply: run a call */
    Py_DECREF(args);                              /* add error checks */

    if (pres != NULL) {
        /* use and decref handler result */
        PyArg_Parse(pres, "s", &cres);
        printf("%s\n", cres);
        Py_DECREF(pres);
    }
}

/*****************************************************/
/* 2) python extension module to register handlers   */
/* python imports this module to set handler objects */
/*****************************************************/

static PyObject *
Register_Handler(PyObject *self, PyObject *args)
{
    /* save Python callable object */
    Py_XDECREF(Handler);                 /* called before? */
    PyArg_Parse(args, "O", &Handler);    /* one argument? */
    Py_XINCREF(Handler);                 /* add a reference */
    Py_INCREF(Py_None);                  /* return 'None': success */
    return Py_None;
}

static PyObject *
Trigger_Event(PyObject *self, PyObject *args)
{
    /* let Python simulate event caught by C */
    static count = 0;
    Route_Event("spam", count++);
    Py_INCREF(Py_None);  
    return Py_None;
}

static struct PyMethodDef cregister_methods[] = {
    {"setHandler",    Register_Handler},       /* name, address */
    {"triggerEvent",  Trigger_Event},  
    {NULL, NULL}
};

void initcregister()                  /* this is called by Python  */
{                                     /* on first "import cregister" */
    (void) Py_InitModule("cregister", cregister_methods);
}