“"和“是“无"和"==没有" [英] What is the difference between " is None " and " ==None "
问题描述
我最近遇到了这种语法，我不知道有什么区别.
I recently came across this syntax, I am unaware of the difference.
如果有人能告诉我与众不同之处，我将不胜感激.
I would appreciate it if someone could tell me the difference.
推荐答案
一个类可以自由实现 比较选择的方式，然后 可以选择与 没有任何意义(实际上是 说得通;如果有人告诉你 从实现 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，因此差异不大.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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