copyreg — Register pickle support functions

The copyreg module defines functions which are used by pickling specific objects while pickling or copying. This module provides configuration information about object constructors(may be factory functions or class instances) which are not classes.

This function is used for declaring object as a valid constructor. An object is not considered as a valid constructor if it is not callable. This function raises TypeError if the object is not callable.

copyreg.pickle(type, function, constructor=None)
This is used to declare function as a “reduction” function for objects of type type. function should return either a string or a tuple containing two or three elements.
The constructor parameter is optional. It 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. TypeError is raised if object is a class or constructor is not callable.

Example :





# Python 3 program to illustrate 
use of copyreg module
import copyreg, 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, )
copyreg.pickle(C, pickle_c)
c = C(1)
d = copy.copy(c)
print (d)
p = pickle.dumps(c)
print (p)


Output :

pickling a C instance...

pickling a C instance...

This article is contributed by Aditi Gupta. If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course.

My Personal Notes arrow_drop_up
Article Tags :

Be the First to upvote.

Please write to us at to report any issue with the above content.