自引用三元 [英] self-referencing ternary

问题描述

我已经做了一段时间了:

I've been doing this for a while:

x = x if x else y

在x可能为 None ， False ， 0 ，''， [] 或 {} .

In all sorts of contexts where x might be None, False, 0, '', [], or {}.

我知道纯粹主义者宁愿我:

I know the purists would rather I:

if not x:
    x = y

但请记住，那不是我的问题.我的问题是:

but forget that, that's not my question. My question is:

除了x是y以外，是否还有 x = x的错误"信息?具体来说，可以像这样进行三元自赋值.

Is there anything 'wrong' with x = x if x else y besides the fact it's a ternary? Specifically, is it ok to have a ternary self-assign like that.

注意

我的问题是 not 是 x = x(如果C否则y 可以).我知道是这样.

My qustion is not is x = x if C else y ok. I know it is.

非常感谢

推荐答案

在c = y的情况下，对 x = x使用三元数并没有错，但是对于 x= x，如果x else y ，则逻辑确实会减少为

There is nothing wrong with using ternary for x = x if c else y, however, in the case of x = x if x else y the logic really does just reduce to

x = x or y

这是因为在Python中， x或y 的计算结果为

This is because in Python x or y evaluates to 'if x is false, then y, else x'

所以 x如果x else y == y如果不是x else x == x或y

So x if x else y == y if not x else x == x or y

很明显， x或y 最清晰，应该使用.

Obviously, x or y is the clearest and should be used.

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