python - 如何 pickle 字典对象？

Question

阅读 pickle 文档后，我的印象是一个类需要实现 __reduce__ 或 __getstate__ 才能正确进行 pickle。但是字典的 pickle 是如何工作的呢？他们没有任何这些属性:

> dict(a=1).__reduce__()

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/home/daniyar/work/Apr24/<ipython-input-30-bc1cbd43305b> in <module>()
----> 1 dict(a=1).__reduce__()

/usr/lib/python2.6/copy_reg.pyc in _reduce_ex(self, proto)
     68     else:
     69         if base is self.__class__:
---> 70             raise TypeError, "can't pickle %s objects" % base.__name__
     71         state = base(self)
     72     args = (self.__class__, base, state)

TypeError: can't pickle dict objects



> dict(a=1).__getstate__()

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
/home/daniyar/work/Apr24/<ipython-input-31-00932fb40067> in <module>()
----> 1 dict(a=1).__getstate__()

AttributeError: 'dict' object has no attribute '__getstate__'

另外，从 dict 派生的类是如何 pickle 的？

Answer 1

The pickle module handles a number of types "natively" .它不本地处理的类型将需要实现 "pickle protocol" .字典和简单的子类是本地处理的。