Source code: Lib/copyreg.py
copyreg module offers a way to define functions used while pickling
specific objects. The
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.
Declares object to be a valid constructor. If object is not callable (and hence not valid as a constructor), raises
pickle(type, function, constructor_ob=None)¶
Declares that function should be used as a “reduction” function for objects of type type. function should return either a string or a tuple containing two or three elements. See the
dispatch_tablefor 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.
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) pickling a C instance... >>> p = pickle.dumps(c) pickling a C instance...