: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 offers a way to define functions used while pickling specific objects. The :mod:`pickle`, :mod:`cPickle`, and :mod:`copy` modules use those functions when pickling/copying those objects. The module 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*. Example ------- The example below would like to show how to register a pickle function and how it will be used: >>> import copy_reg, copy, pickle >>> class C(object): ... def __init__(self, a): ... self.a = a ... >>> def pickle_c(c): ... print("pickling a C instance...") ... return C, (c.a,) ... >>> copy_reg.pickle(C, pickle_c) >>> c = C(1) >>> d = copy.copy(c) pickling a C instance... >>> p = pickle.dumps(c) pickling a C instance...