使用deepcopy与字典里面的对象的问题 [英] Issue using deepcopy with dictionary inside object

问题描述

阅读文档，我明白 copy.deepcopy（obj）递归地复制这一个内的任何其他对象，但是当我运行时：

Reading the documentation, I understood that copy.deepcopy(obj) copies recursively any other object inside this one, but when I run:

>>> import copy
>>> class SomeObject:
...     a=1
...     b={1:1,2:2}
... 
>>> o1=SomeObject()
>>> o2=copy.deepcopy(o1)
>>> id(o1)
140041523635624
>>> id(o2)
140041523635912
>>> id(o1.b)
30087968
>>> id(o2.b)
30087968

似乎没有复制字典里面'O1'。任何人都可以告诉我，如果我做错了什么，或者如何获取对象内的字典副本？

It does not seem to be copying the dictionary inside 'o1'. Can anyone tell me if I am doing something wrong, or how can I get a copy of the dictionary inside the object?

谢谢

推荐答案

深层拷贝仅复制实例属性。您的 b 属性是一个类属性。

Deepcopy only copies instance attributes. Your b attribute is a class attribute, instead.

即使您没有 创建一个副本，但是一个新的实例 SomeObject 手动， b 仍然会被共享：

Even if you did not create a copy but a new instance of SomeObject manually, b would still be shared:

>>> class SomeObject:
...     a=1
...     b={1:1,2:2}
... 
>>> so1 = SomeObject()
>>> so2 = SomeObject()
>>> so1.b is so2.b
True
>>> so1.b is SomeObject.b
True

Make b 一个实例属性：

Make b an instance attribute:

>>> import copy
>>> class SomeObject:
...     a = 1
...     def __init__(self):
...         self.b = {1: 1, 2: 2}
... 
>>> so1 = SomeObject()
>>> so2 = copy.deepcopy(so1)
>>> so1.b is so2.b
False

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