提高条件表达式的陈述

Following "Samurai principle", I'm trying to do this on my functions but seems it's wrong...

遵循“武士原则”，我试图在我的功能上做到这一点，但似乎是错的......

return <value> if <bool> else raise <exception>

Is there any other "beautiful" way to do this? Thanks

有没有其他“漂亮”的方式来做到这一点？谢谢

4 个解决方案

#1

Inline/ternary if is an expression, not a statement. Your attempt means "if bool, return value, else return the result of raise expression" - which is nonsense of course, because raise exception is itself a statement not an expression.

内联/三元if是表达式，而不是语句。你的尝试意味着“如果bool，返回值，否则返回raise表达式的结果” - 这当然是无稽之谈，因为raise异常本身就是一个语句而不是表达式。

There's no way to do this inline, and you shouldn't want to. Do it explicitly:

内联无法做到这一点，你不应该这样做。明确地做：

if not bool:
    raise MyException
return value

#2

If you absolutely want to raise in an expression, you could do

如果你绝对想要表达，你可以做到

def raiser(ex): raise ex

return <value> if <bool> else raiser(<exception>)

This "tries" to return the return value of raiser(), which would be None, if there was no unconditional raise in the function.

如果函数中没有无条件加注，则“尝试”返回raiser（）的返回值，该值将为None。

#3

Well, you could test for the bool separately:

好吧，你可以分别测试bool：

if expr: raise exception('foo')
return val

That way, you could test for expr earlier.

这样，你可以先测试expr。

#4

I like to do it with assertions, so you emphasize that that member must to be, like a contract.

我喜欢用断言来做，所以你要强调那个成员必须像合同一样。

>>> def foo(self):
...     assert self.value, "Not Found"
...     return self.value

#1