“是无"和“无"有什么区别?和“==无" [英] What is the difference between "is None" and "== None"

问题描述

我最近遇到了这种语法，我不知道其中的区别.

I recently came across this syntax, I am unaware of the difference.

如果有人能告诉我其中的区别，我将不胜感激.

I would appreciate it if someone could tell me the difference.

推荐答案

答案已经解释 这里.

引用:

一个类可以自由实现比较它选择的任何方式，它可以选择对比没有任何意思(实际上说得通;如果有人告诉你从实现 None 对象从头开始，你还能怎么做将 True 与自身进行比较?).

A class is free to implement comparison any way it chooses, and it can choose to make comparison against None mean something (which actually makes sense; if someone told you to implement the None object from scratch, how else would you get it to compare True against itself?).

实际上，由于自定义比较运算符很少见，因此没有太大区别.但是您应该使用 is None 作为一般规则.

Practically-speaking, there is not much difference since custom comparison operators are rare. But you should use is None as a general rule.

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