Shared Objects in Python
========================

ctypes is a foreign function library for Python. It provides C compatible data
types, and allows calling functions in DLLs or shared libraries. It can be used
to wrap these libraries in pure Python.

Eine Einfache Library
---------------------
First let us write a small c-library, a simple Hello-World example is
sufficient:

.. code-block:: c

    #include <stdio.h>

    void myprint(void);

    void myprint()
    {
        printf("Hello World\n");
    }

Now, compile it as a shared library:

.. code:: bash

    $ gcc -shared -Wl,-soname,testlib -o testlib.so -fPIC testlib.c

Zugriff auf Shared Objects
--------------------------
In Python, write a wrapper using ctypes:

.. code-block:: python

    import ctypes

    testlib = ctypes.CDLL("testlib.so")
    testlib.myprint()

and execute it like this:

.. code:: bash

    $ python cwrapper.py

You should see the following output:

.. code:: bash

    % python cwrapper.py
    Hello World