如何用自引用和从带有槽的类中pickle和unpickle对象?

当这个对象通过它的一个属性引用自己时,从带有槽的类中pickle对象的正确方法是什么?下面是一个简单的例子,我的当前实现,我不确定它是否100%正确:

import weakref
import pickle

class my_class(object):

    __slots__ = ('an_int', 'ref_to_self', '__weakref__')

    def __init__(self):
        self.an_int = 42
        self.ref_to_self = weakref.WeakKeyDictionary({self: 1})

    # How to best write __getstate__ and __setstate__?
    def __getstate__(self):

        obj_slot_values = dict((k, getattr(self, k)) for k in self.__slots__)
        # Conversion to a usual dictionary:
        obj_slot_values['ref_to_self'] = dict(obj_slot_values['ref_to_self'])
        # Unpicklable weakref object:
        del obj_slot_values['__weakref__']
        return obj_slot_values

    def __setstate__(self, data_dict):
        # print data_dict
        for (name, value) in data_dict.iteritems():
            setattr(self, name, value)
        # Conversion of the dict back to a WeakKeyDictionary:
        self.ref_to_self = weakref.WeakKeyDictionary(
            self.ref_to_self.iteritems())

例如,这可以通过以下方式进行测试:

def test_pickling(obj):
    "Pickles obj and unpickles it.  Returns the unpickled object"

    obj_pickled = pickle.dumps(obj)
    obj_unpickled = pickle.loads(obj_pickled)

    # Self-references should be kept:
    print "OK?", obj_unpickled == obj_unpickled.ref_to_self.keys()[0]
    print "OK?", isinstance(obj_unpickled.ref_to_self,
                            weakref.WeakKeyDictionary)

    return obj_unpickled

if __name__ == '__main__':
    obj = my_class()
    obj_unpickled = test_pickling(obj)
    obj_unpickled2 = test_pickling(obj_unpickled)

这是正确/可靠的实现吗?该如何 __getstate__ 和 __setstate__ 写成 my_class 从类继承 __slots__ ?里面有内存泄漏吗 α-塞特他汀 因为“循环”口述?

有句话在 PEP 307 这让我想知道是不是腌制 米亚尔 对象以一种健壮的方式是完全可能的:

这个 γ-GETSteste* 方法应返回表示对象状态的可选取值,而不引用对象本身。

这是否与对象本身的引用被pickle这一事实相冲突?

这是很多问题:任何评论、评论或建议都会非常感谢!