# 3.16 `copy_reg` -- Register `pickle` support functions

The `copy_reg` module provides support for the `pickle` and `cPickle` modules. The `copy` module is likely to use this in the future as well. It 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])
  Declares that function should be used as a ``reduction'' function for objects of type type; type should not a class object. function should return either a string or a tuple. 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. `TypeError` will be raised if object is a class or constructor is not callable.