Updating Python modules in C for Python3

[arunppsg]

The post on Python modules in C is one of the best introductory post which I have ever seen on that topic. It will be great if it could be updated to work with Python3. To make it work, we need to do the following changes:

• Use PyModuleDef to define the module in _chi2.c

static PyModuleDef chi2_module = {
    PyModuleDef_HEAD_INIT,
    .m_name = "_chi2",
    .m_doc = module_docstring,
    .m_size = -1,
    .m_methods = module_methods,
};

• Use PyInit__chi2 instead of init_chi2, update the function to return NULL when the module does not get initialized and PyModule_Create instead of Py_InitModule3. The updated version:

PyMODINIT_FUNC PyInit__chi2(void)
{ 
  PyObject *m = PyModule_Create(&chi2_module);
  if (m == NULL) {
    return NULL; 
  }
  
  /* Load numpy functionality */
  import_array();

  return m;
}

Thank you for the wonderful post.