# `copyreg` --- Register `pickle` support functions

Code source : Lib/copyreg.py

The `copyreg` module offers a way to define functions used while pickling specific objects. The `pickle` and `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.

copyreg.constructor(object)

  Déclare object comme étant un constructeur valide. Si object n'est pas appelable (et n'est donc pas un constructeur valide), l'erreur `TypeError` est levée.

copyreg.pickle(type, function, constructor_ob=None)

  Declares that function should be used as a "reduction" function for objects of type type. function must return either a string or a tuple containing between two and six elements. See the `dispatch_table` for more details on the interface of function.

  The constructor_ob parameter is a legacy feature and is now ignored, but if passed it must be a callable.

  Note that the `dispatch_table` attribute of a pickler object or subclass of `pickle.Pickler` can also be used for declaring reduction functions.

## Exemple

L'exemple si-dessous essaye de démontrer comment enregistrer une fonction pickle et comment elle sera utilisée :

    >>> import copyreg, copy, pickle
    >>> class C:
    ...     def __init__(self, a):
    ...         self.a = a
    ...
    >>> def pickle_c(c):
    ...     print("pickling a C instance...")
    ...     return C, (c.a,)
    ...
    >>> copyreg.pickle(C, pickle_c)
    >>> c = C(1)
    >>> d = copy.copy(c)
    pickling a C instance...
    >>> p = pickle.dumps(c)
    pickling a C instance...