Python，我应该基于__eq__实现__ne __（）运算符吗？ [英] Python, should I implement __ne__() operator based on __eq__?

问题描述

我有一个类，我要覆盖 __ eq __（）运算符。似乎有意义的是，我应该重写 __ ne __（）运算符，但它是有意义的实现 __ ne __ __ eq __ 如此？

I have a class where I want to override the __eq__() operator. It seems to make sense that I should override the __ne__() operator as well, but does it make sense to implement __ne__ based on __eq__ as such?

class A:
    def __eq__(self, other):
        return self.value == other.value

    def __ne__(self, other):
        return not self.__eq__(other)

或者有些东西，我错过了Python使用这些运算符，好主意？

Or is there something that I'm missing with the way Python uses these operators that makes this not a good idea?

推荐答案

是的，这很好。实际上，文档会敦促您定义 __ ne __ 当您定义 __ eq __ ：

Yes, that's perfectly fine. In fact, the documentation urges you to define __ne__ when you define __eq__:

$ b的比较运算符。 x == y 的
真值并不意味着 x！= y
假。因此，当定义
__ eq __（）时，还应该定义 __ ne __（）表现如预期。

There are no implied relationships among the comparison operators. The truth of x==y does not imply that x!=y is false. Accordingly, when defining __eq__(), one should also define __ne__() so that the operators will behave as expected.

在很多情况下（例如这一个），它将是简单的否定结果 __ eq __ ，但不总是。

In a lot of cases (such as this one), it will be as simple as negating the result of __eq__, but not always.

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