Initializing new types

[Carlos P.]

Hi!

I´m trying to figure out how to write C extensions with the
2.2 "type==class" new API. Below is an excerpt of a short program
I´m writing as a starter. The most important question is: am
I using PyType_Ready() as I should? There´s little documentation
about this function so I have taken a look at the implementation.
Also, there´s a mail from Guido in python-dev that states:

"""
Because we currently don't explicitly initialize all type object, most
types are auto-initialized on their first attribute requested from one
of their instances, by PyObject_GenericGetAttr(): 
"""

and then:

"""
Yes, this is a mess.  We may be better off requesting that all types
are initialized explicitly;
"""

But I´m not sure if the way to explicitly initialize the type is
the one I´m following. Besides this, the code in xxsubtype.c confuses
me a little more because of the double initialization with different
base types:

"""
DL_EXPORT(void)
initxxsubtype(void)
{
	PyObject *m, *d;

	spamdict_type.tp_base = &PyDict_Type;
	if (PyType_Ready(&spamdict_type) < 0)
		return;

	spamlist_type.tp_base = &PyList_Type;
	if (PyType_Ready(&spamlist_type) < 0)
		return;
	....
}
"""

And a last thing: PEP 253 says something about PyType_InitDict(). But
I couldn´t find this function in the sources. Perhaps the PEP is a
little outdated, isn´t it?

Well, as I´ve said before, my sample code is listed below. And after
it,
an alternative one that shows what I think is not the right way (or at
least
the best way) to initialize a type. (But I´m not sure at all)

Thank you in advance,
   Carlos

Sample code:

static PyTypeObject Turing_type = {
    PyObject_HEAD_INIT(NULL)
    0,
    "Turing",
    sizeof(Turing_object),
    0,
    (destructor)Turing_dealloc,	 /*tp_dealloc*/
	....
    Py_TPFLAGS_DEFAULT |
    Py_TPFLAGS_BASETYPE,	 /* tp_flags */
    Turing_doc,			 /* tp_doc */
	....
    Turing_methods,		 /* tp_methods */
    Turing_members,		 /* tp_members */
	....
    Turing_new,			 /* tp_new */
	....
};

DL_EXPORT(void) initturing(void) {

  PyObject *d, *m;

  if(PyType_Ready(&Turing_type) < 0)
    return;
  ....
  m = Py_InitModule("turing", turing_methods);
  d = PyModule_GetDict(m);
  ....
  PyDict_SetItemString(d, "Turing", (PyObject*) &Turing_type);
  ....
}


Alternative code:

DL_EXPORT(void) initturing(void) {

  PyObject *d, *m;

  // Non-constant fields initialized here:
  Turing_type.ob_type = &PyType_Type;
  Turing_type.tp_getattro = PyObject_GenericGetAttr;
  Turing_type.tp_alloc = PyType_GenericAlloc;
  Turing_type.tp_free = _PyObject_Del;
  ....
  m = Py_InitModule("turing", turing_methods);
  d = PyModule_GetDict(m);
  ....
  PyDict_SetItemString(d, "Turing", (PyObject*) &Turing_type);
  ....
}