:mod:`cPickle` --- A faster :mod:`pickle`
=========================================

.. module:: cPickle
   :synopsis: Faster version of pickle, but not subclassable.
.. moduleauthor:: Jim Fulton <jim@zope.com>
.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>


.. index:: module: pickle

The :mod:`cPickle` module supports serialization and de-serialization of Python
objects, providing an interface and functionality nearly identical to the
:mod:`pickle` module.  There are several differences, the most important being
performance and subclassability.

First, :mod:`cPickle` can be up to 1000 times faster than :mod:`pickle` because
the former is implemented in C.  Second, in the :mod:`cPickle` module the
callables :func:`Pickler` and :func:`Unpickler` are functions, not classes.
This means that you cannot use them to derive custom pickling and unpickling
subclasses.  Most applications have no need for this functionality and should
benefit from the greatly improved performance of the :mod:`cPickle` module.

The pickle data stream produced by :mod:`pickle` and :mod:`cPickle` are
identical, so it is possible to use :mod:`pickle` and :mod:`cPickle`
interchangeably with existing pickles. [#]_

There are additional minor differences in API between :mod:`cPickle` and
:mod:`pickle`, however for most applications, they are interchangeable.  More
documentation is provided in the :mod:`pickle` module documentation, which
includes a list of the documented differences.


.. rubric:: Footnotes

.. [#] Since the pickle data format is actually a tiny stack-oriented programming
   language, and some freedom is taken in the encodings of certain objects, it is
   possible that the two modules produce different data streams for the same input
   objects.  However it is guaranteed that they will always be able to read each
   other's data streams.