我在 python 2.7 上使用 pickle。我正在尝试调用我覆盖的两种方法 __getstate__ 和 __getnewargs__ 。我不能 pickle 属性 c 因为它是类 D 的一个实例。
nn = C(7, 2)
nn.d = 1
pickle.dump(nn, open('c_save.p', 'wb'))
nn2 = pickle.load(open('c_save.p', 'rb'))
print nn2.__dict__
返回:
getstate was called
setstate was called
{'a': 7, 'b': 2, 'd': 1}
我没有看到应该创建属性 c 的 __getnewargs__ 调用。
我的代码:
import pickle
class D(object):
def __init__(self, i, j):
self.i = i
self.j = j
class C(object):
def __init__(self, a, b):
self.a = a
self.b = b
self.c = D(a, b)
self.d = 0
def __getstate__(self):
print 'getstate was called'
odict = self.__dict__.copy()
del odict['c']
return odict
def __getnewargs__(self):
print 'getnewargs was called'
return (self.b,self.a)
def __setstate__(self, dict):
print 'setstate was called'
self.__dict__.update(dict)
最佳答案
来自docs :
New-style types can provide a getnewargs() method that is used for protocol 2.
对于 pickle.dump :
If the protocol parameter is omitted, protocol 0 is used.
因此，您必须像这样显式地将 pickle 协议(protocol)设置为 2:
pickle.dump(nn, open('c_save.p', 'wb'), protocol=2)
关于python - pickle : using both __getstate__ and __getnewargs__，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/43538628/