# copy these lines to a file named: setup.py
# To build and install the elemlist module you need the following
# setup.py file that uses the distutils:
from distutils.core import setup, Extension
setup (name = "elemlist",
version = "1.0",
maintainer = "Alex Martelli",
maintainer_email = "aleax@aleax.it",
description = "Sample Python module",
ext_modules = [Extension('elemlist',sources=['elemlist.c'])]
)
# end of file: setup.py
/* copy these lines to a file named: elemlist.c */
/* and here comes elemlist.c itself with really minimal comments: */
#include "Python.h"
/* type-definition & utility-macros */
typedef struct {
PyObject_HEAD
PyObject *car, *cdr;
} cons_cell;
staticforward PyTypeObject cons_type;
/* a typetesting macro (we don't use it here) */
#define is_cons(v) ((v)->ob_type == &cons_type)
/* macros to access car & cdr, both as lvalues & rvalues */
#define carof(v) (((cons_cell*)(v))->car)
#define cdrof(v) (((cons_cell*)(v))->cdr)
/* ctor (factory-function) and dtor */
static cons_cell*
cons_new(PyObject *car, PyObject *cdr)
{
cons_cell *cons = PyObject_NEW(cons_cell, &cons_type);
if(cons) {
cons->car = car; Py_INCREF(car); /* INCREF when holding a PyObject* */
cons->cdr = cdr; Py_INCREF(cdr); /* ditto */
}
return cons;
}
static void
cons_dealloc(cons_cell* cons)
{
/* DECREF when releasing previously-held PyObject*'s */
Py_DECREF(carof(cons)); Py_DECREF(cdrof(cons));
PyObject_DEL(cons);
}
/* Python type-object */
statichere PyTypeObject cons_type = {
PyObject_HEAD_INIT(0) /* initialize to 0 to ensure Win32 portability */
0, /*ob_size*/
"cons", /*tp_name*/
sizeof(cons_cell), /*tp_basicsize*/
0, /*tp_itemsize*/
/* methods */
(destructor)cons_dealloc, /*tp_dealloc*/
/* implied by ISO C: all zeros thereafter */
};
/* module-functions */
static PyObject*
cons(PyObject *self, PyObject *args) /* the exposed factory-function */
{
PyObject *car, *cdr;
if(!PyArg_ParseTuple(args, "OO", &car, &cdr))
return 0;
return (PyObject*)cons_new(car, cdr);
}
static PyObject*
car(PyObject *self, PyObject *args) /* car-accessor */
{
PyObject *cons;
if(!PyArg_ParseTuple(args, "O!", &cons_type, &cons)) /* type-checked */
return 0;
return Py_BuildValue("O", carof(cons));
}
static PyObject*
cdr(PyObject *self, PyObject *args) /* cdr-accessor */
{
PyObject *cons;
if(!PyArg_ParseTuple(args, "O!", &cons_type, &cons)) /* type-checked */
return 0;
return Py_BuildValue("O", cdrof(cons));
}
static PyMethodDef elemlist_methods[] = {
{"cons", cons, METH_VARARGS},
{"car", car, METH_VARARGS},
{"cdr", cdr, METH_VARARGS},
{0, 0}
};
/* module entry-point (module-initialization) function */
void
initelemlist(void)
{
/* Create the module and add the functions */
PyObject *m = Py_InitModule("elemlist", elemlist_methods);
/* Finish initializing the type-objects */
cons_type.ob_type = &PyType_Type;
}
/* end of file: elemlist.c */
