有没有办法让python pickle忽略“它不是同一对象"?错误 [英] Is there a way to make python pickle ignore "it's not the same object " errors

问题描述

有没有办法让python pickle忽略它不是同一对象"错误?

Is there a way to make python pickle ignore "it's not the same object " errors?

我正在使用Mock编写测试，以对datetime.utcnow()产生的结果进行精细控制.我正在使用的代码对时间敏感，因此模拟补丁可使其易于测试.

I'm writing a test using Mock to have fine grain control over the results that datetime.utcnow() produces. The code I'm using is time sensitive so mock's patch makes it easy to test.

相同的测试需要腌制对象并将结果发送到远程服务器.出于测试目的，如果标准日期时间是由远程服务器腌制并接收的，则一切正常.

The same tests need to pickle objects and send the results to a remote server. For the purpose of the test if a standard datetime was pickled and received by the remote server everything would be fine.

不幸的是，泡菜模块正在倒装，并出现以下错误:

Unfortunately the pickle module is barfing with the following error:

无法腌制<键入'datetime.datetime'> ;:与以下对象不同 datetime.datetime

Can't pickle <type 'datetime.datetime'>: it's not the same object as datetime.datetime

这是重现该错误的最小示例.

Here is a minimal example to reproduce the error.

from mock import patch
from datetime import datetime
import pickle

class MockDatetime(datetime):
  frozendt = datetime(2011,05,31)

  @classmethod
  def advance(cls, **kw):
    cls.frozendt = cls.frozendt + timedelta(**kw)

  @classmethod
  def utcnow(cls):
    return cls.frozendt

@patch('datetime.datetime', MockDatetime)
def test():
  pickle.dumps(datetime.utcnow())

if __name__ == '__main__':
  test()

是否存在某些__reduce__和__getstate__方法的组合，可能会使泡菜机械误以为MockDatetime是我泡菜时的日期时间?

Is there some combo of __reduce__ and __getstate__ methods that might trick the pickle machinery into thinking MockDatetime is a datetime when I pickle?

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Looking at the where to patch section in the documentation I see this advice:

基本原理是在使用的地方打补丁，该地方不一定与定义的地方相同.

The basic principle is that you patch where an object is used, which is not necessarily the same place as where it is defined.

按照此建议，我尝试替换:

Following this recommendation, I've tried to replace:

@patch('datetime.datetime', MockDatetime)

具有:

@patch('__main__.datetime', MockDatetime)

，我没有从pickle收到任何错误.另外，我添加了print语句以确保datetime确实已被修补，并且我获得了预期的值.

and I didn't get any error from pickle. Also, I added a print statement to make sure that datetime was really being patched and I got the expected value.

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