call_external_python_function.c

static PyObject *get_external_function(const char *module_name, const char *function_name)
{
    PyObject *module = PyImport_ImportModule(module_name);
    PyObject *globals = PyModule_GetDict(module);
    PyObject *function = PyDict_GetItemString(globals, function_name);
    Py_DecRef(module);
    return function;
}

static PyObject *call_external_method(
        const char *module_name,
        const char *function_name,
        PyObject *self, PyObject *args, PyObject *kwds)
{
    PyObject *function = get_external_function(module_name, function_name);
    int args_length = PyTuple_Size(args);
    PyObject *new_args = PyTuple_New(1 + args_length);

    Py_IncRef(self);
    PyTuple_SET_ITEM(new_args, 0, self);

    for (int i = 0; i < args_length; i++) {
        PyObject *value = PyTuple_GetItem(args, i);
        Py_IncRef(value);
        PyTuple_SET_ITEM(new_args, i + 1, value);
    }

    PyObject *ret = PyEval_CallObjectWithKeywords(function, new_args, kwds);
    Py_DecRef(new_args);

    return ret;
}