在Python中腌制weakref

Question

我对Python还是很陌生，甚至对酸洗也比较新。我有一个类Vertex(ScatterLayout)有__getnewargs__()：

def __getnewargs__(self):
    return (self.pos, self.size, self.idea.text)

我的理解是，这将使泡菜从对象__getnewargs__()而不是从字典中提取对象。

在以下方法中（在另一个类中MindMapApp(App)）调用泡菜：

def save(self):
    vertices = self.mindmap.get_vertices()
    edges = self.mindmap.get_edges()

    output = open('mindmap.pkl', 'wb')

    #pickle.dump(edges, output, pickle.HIGHEST_PROTOCOL)
    pickle.dump(vertices, output, pickle.HIGHEST_PROTOCOL)

    output.close()

当我调用该save()方法时，出现以下错误：

pickle.PicklingError: Can't pickle <type 'weakref'>: it's not found as __builtin__.weakref

我缺少或不了解什么？我也尝试实现__getstate__()/__setstate__(state)组合，结果相同。

Answer 1

你绝对可以泡菜a weakref，泡菜adict和a
list。但是，实际上它们包含的内容很重要。如果dict或list包含不可拾取的intem，则酸洗将失败。如果您想泡菜weakref，就必须使用dill而不是pickle。weakref但是，未经挑选的反序列化为无效参考。

>>> import dill
>>> import weakref
>>> dill.loads(dill.dumps(weakref.WeakKeyDictionary()))
<WeakKeyDictionary at 4528979192>
>>> dill.loads(dill.dumps(weakref.WeakValueDictionary()))
<WeakValueDictionary at 4528976888>
>>> class _class:
...   def _method(self):
...     pass
... 
>>> _instance = _class()
>>> dill.loads(dill.dumps(weakref.ref(_instance)))
<weakref at 0x10d748940; dead>
>>> dill.loads(dill.dumps(weakref.ref(_class())))
<weakref at 0x10e246a48; dead>
>>> dill.loads(dill.dumps(weakref.proxy(_instance)))
<weakproxy at 0x10e246b50 to NoneType at 0x10d481598>
>>> dill.loads(dill.dumps(weakref.proxy(_class())))
<weakproxy at 0x10e246ba8 to NoneType at 0x10d481598>