copyreg
Source code: Lib/copyreg.py
pair: module; pickle pair: module; copy
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.
constructor(object)
Declares object to be a valid constructor. If object is not callable (and hence not valid as a constructor), raises TypeError.
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 ~pickle.Pickler.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 ~pickle.Pickler.dispatch_table attribute of a pickler object or subclass of pickle.Pickler can also be used for declaring reduction functions.
The example below would like to show how to register a pickle function and how it will be used:
>>> 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) # doctest: +SKIP pickling a C instance... >>> p = pickle.dumps(c) # doctest: +SKIP pickling a C instance...