mypy，输入提示:Union[float, int] ->有数字类型吗? [英] mypy, type hint: Union[float, int] -> is there a Number type?

问题描述

mypy 真的很方便，可以捕获很多错误，但是当我编写科学"应用程序时，我经常会这样做:

mypy is really handy and catches a lot of bugs, but when I write "scientific" applications, I often end up doing:

def my_func(number: Union[float, int]):
    # Do something

number 是浮点数或整数，取决于用户的输入.有官方的方法吗?

number is either a float or int, depending on the user's input. Is there an official way to do that?

推荐答案

使用 float only，因为 int 隐含在该类型中:

Use float only, as int is implied in that type:

def my_func(number: float):

PEP 484 类型提示 特别声明:

这个 PEP 不是要求用户编写导入数字然后使用 numbers.Float 等，而是提出了一个几乎同样有效的简单快捷方式:当参数被注释为具有类型时float，int 类型的参数是可以接受的；类似的，对于注释为 complex 类型的参数，float 或 int 类型的参数是可以接受的.

Rather than requiring that users write import numbers and then use numbers.Float etc., this PEP proposes a straightforward shortcut that is almost as effective: when an argument is annotated as having type float, an argument of type int is acceptable; similar, for an argument annotated as having type complex, arguments of type float or int are acceptable.

(粗体强调我的).

理想情况下，您仍会使用 numbers.Real:

Ideally you would still use numbers.Real:

from numbers import Real

def my_func(number: Real):

因为它也接受 fractions.Fraction() 和 decimal.Decimal() 对象；数字金字塔不仅仅是整数和浮点值.

as that would accept fractions.Fraction() and decimal.Decimal() objects as well; the number pyramid is broader than just integers and floating point values.

但是，当使用 mypy 进行类型检查时，这些当前不起作用，请参阅 Mypy #3186.

However, these are not currently working when using mypy to do your type checking, see Mypy #3186.

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