cpython/Doc/library/copy_reg.rst

:mod:`copy_reg` --- Register :mod:`pickle` support functions
============================================================

.. module:: copy_reg
   :synopsis: Register pickle support functions.

.. note::
   The :mod:`copy_reg` module has been renamed to :mod:`copyreg` in Python 3.
   The :term:`2to3` tool will automatically adapt imports when converting your
   sources to Python 3.

.. index::
   module: pickle
   module: cPickle
   module: copy

The :mod:`copy_reg` module provides support for the :mod:`pickle` and
:mod:`cPickle` modules.  The :mod:`copy` module is likely to use this in the
future as well.  It provides configuration information about object constructors
which are not classes.  Such constructors may be factory functions or class
instances.


.. function:: constructor(object)

   Declares *object* to be a valid constructor.  If *object* is not callable (and
   hence not valid as a constructor), raises :exc:`TypeError`.


.. function:: pickle(type, function[, constructor])

   Declares that *function* should be used as a "reduction" function for objects of
   type *type*; *type* must not be a "classic" class object.  (Classic classes are
   handled differently; see the documentation for the :mod:`pickle` module for
   details.)  *function* should return either a string or a tuple containing two or
   three elements.

   The optional *constructor* parameter, if provided, is a callable object which
   can be used to reconstruct the object when called with the tuple of arguments
   returned by *function* at pickling time.  :exc:`TypeError` will be raised if
   *object* is a class or *constructor* is not callable.

   See the :mod:`pickle` module for more details on the interface expected of
   *function* and *constructor*.