Python Advanced Tutorial 9 - C Extensions

This is tutorial on how to extend Python with the C Programming Language. All Links and Slides will be in the description. Subscribe for more cool stuff!

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With Python 3.x the way extensions are written has changed. instead of the "PyMODINIT_FUNC initmyModule(void)" you now use a static structure of "PyModuleDef" which holds all the information to your module and then use PyInit_MyModule(void) and create the Module inside of that Function with PyModule_Create

this would be the new Source Code:

#include<Python.h>

int Cfib(int n)
{
if(n < 2)
return n;
else
return Cfib(n-1) + Cfib(n-2);
}

static PyObject* fib(PyObject* self, PyObject* args)
{
int n;

if (!PyArg_ParseTuple(args, "i", &n))
return NULL;

return Py_BuildValue("i", Cfib(n));
}

static PyObject* version(PyObject* self)
{
return Py_BuildValue("s", "Version: 1.0");
}

static PyMethodDef myMethods[] = {
{"fib", fib, METH_VARARGS, "Calculates the Fibonacci number."},
{"version", (PyCFunction)version, METH_NOARGS, "Returns the version."},
{NULL, NULL, 0, NULL}
};


static struct PyModuleDef myModule = {
PyModuleDef_HEAD_INIT,
"myModule", /* Module Name */
NULL, /* Optional Module Description */
-1,
myMethods /* Methods Array */
/* Along with a few other optional parameters just look PyModuleDef up*/
};

PyMODINIT_FUNC PyInit_myModule(void)
{
return PyModule_Create(&myModule);
}



The best Way to make it compatible with Python 3.x and older versions would be to include both ways to Initialize a module by separating them with the following Preprocessor definition

#if PY_MAJOR_VERSION >= 3
/*Put the new Initialization here*/
#else
/*The old one here*/
#endif


There are probably spelling mistakes in the source so dont expect this to compile right away :P

[HealmBreaker]

I am astonished at no comments despite so many views, this is for python2.x and not 3, there are few changes needed to be made to make it work in python3