copyreg — Register pickle support functions

Вихідний код: 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)

Оголошує object як дійсний конструктор. Якщо object не можна викликати (і, отже, недійсний як конструктор), викликає TypeError.

copyreg.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 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 dispatch_table attribute of a pickler object or subclass of pickle.Pickler can also be used for declaring reduction functions.

приклад

Наведений нижче приклад показує, як зареєструвати функцію pickle і як вона буде використовуватися:

>>> 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...