copyreg — Register pickle support functions¶
Source code: 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)¶
- Declares object to be a valid constructor. If object is not callable (and hence not valid as a constructor), raises - TypeError.
- 
copyreg.pickle(type, function, constructor=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. - 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. - TypeErrorwill be raised if object is a class or constructor is not callable.- See the - picklemodule for more details on the interface expected of function and constructor. Note that the- dispatch_tableattribute of a pickler object or subclass of- pickle.Picklercan also be used for declaring reduction functions.
Example¶
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...