iowait -- Platform-independent module for I/O completion events
===============================================================

Different operating systems provide different ways to wait for I/O completion
events: there's ``select()``, ``poll()``, ``epoll()`` and ``kqueue()``. For
cross-platform applications it can be a pain to support all this system
functions, especially because each one provides a different interface.

IOWait solves this problem by providing a unified interface and using always
the best and faster function available in the platform. Its only limitation is
that, on Windows, it only works for sockets.

This library is compatible both with Python 2 and 3.


Example
-------

Here is an usage example. First, we need to create a pair of sockets:

    >>> import socket
    >>> a, b = socket.socketpair()

Then we create a ``IOWait`` object. This object is essentially a wrapper around
a system function (such as ``select()`` or ``poll()``), but exposes always the
same methods and behaves always the same.

    >>> from iowait import IOWait
    >>> waitobj = IOWait()

Now we can watch the first socket for read events in this way:

    >>> waitobj.watch(a, read=True)

We send some data over the other socket:

    >>> b.sendall('this is a test')

Calling ``wait()`` on the ``IOWait`` object will tell us that the socket a is
ready to be read:

    >>> events = waitobj.wait()
    >>> events #doctest:+ELLIPSIS
    [(<socket object, ...>, True, False)]

The return value of ``wait()`` is a list of three-tuples in the format:
``(file, read, write)``, where ``file`` is a file-like object, ``read`` and
``write`` tell respectively whether the file is ready to be read or written.

Once all the data has been read, the next call to ``wait()`` will block
forever, unless a timeout is specified:

    >>> a.recv(14)
    'this is a test'
    >>> waitobj.wait(0.0)
    []
