如何通过函数注释指示函数需要一个函数作为参数，或返回一个函数? [英] How to indicate that a function expects a function as a parameter, or returns a function, via function annotations?

问题描述

你可以在python 3中使用函数注解来指示参数的类型和返回值，像这样:

You can use function annotations in python 3 to indicate the types of the parameters and return value, like so:

def myfunction(name: str, age: int) -> str:
    return name + str(age) #usefulfunction

但是如果您正在编写一个函数，它需要一个函数作为参数，或者返回一个函数呢?

But what if you were writing a function that expects a function as a parameter, or returns one?

我意识到您可以为注释编写任何有效的表达式，因此我可以将函数"写为字符串，但这是最好的/唯一的方法吗?有没有像内置类型 int/float/str/list/dict 等?我知道 callable，但我想知道是否还有其他东西.

I realize that you can write any valid expression in for the annotations, so I could write "function" as a string, but is that the best/only way of doing it? Is there nothing like the built-in types int/float/str/list/dict etc? I'm aware of callable, but I'm wondering if there's anything else.

推荐答案

没有为注释定义样式.使用 callable、types.FunctionType 或字符串.

There's no style defined for annotations. Either use callable, types.FunctionType or a string.

PS:callable 在 Python 3.0 和 3.1 中不可用

PS: callable was not available in Python 3.0 and 3.1

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