source: python/trunk/Doc/library/copy_reg.rst

Last change on this file was 391, checked in by dmik, 11 years ago

python: Merge vendor 2.7.6 to trunk.
  • Property svn:eol-style set to native
File size: 2.3 KB

: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 fuctions 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...
Note: See TracBrowser for help on using the repository browser.