功能注释 [英] Function annotations

问题描述

我真的很喜欢函数注释，因为它们使我的代码更加清晰.但是我有一个问题:如何注释以另一个函数作为参数的函数?还是返回一个?

I really do like function annotations, because they make my code a lot clearer. But I have a question: How do you annotate a function that takes another function as an argument? Or returns one?

def x(f: 'function') -> 'function':
    def wrapper(*args, **kwargs):
        print("{}({}) has been called".format(f.__name__, ", ".join([repr(i) for i in args] + ["{}={}".format(key, value) for key, value in kwargs])))
        return f(*args, **kwargs)
    return wrapper

我不想做 Function = type(lambda:None)以便在注释中使用它.

And I don't want to do Function = type(lambda: None) to use it in annotations.

推荐答案

使用新的 <在Python 3.5中添加了code> typing 类型提示支持；函数是 callables ，您不需要函数类型，而是需要可以调用的东西:

Use the new typing type hinting support added to Python 3.5; functions are callables, you don't need a function type, you want something that can be called:

from typing import Callable, Any

def x(f: Callable[..., Any]) -> Callable[..., Any]:
    def wrapper(*args, **kwargs):
        print("{}({}) has been called".format(f.__name__, ", ".join([repr(i) for i in args] + ["{}={}".format(key, value) for key, value in kwargs])))
        return f(*args, **kwargs)
    return wrapper

上面的代码指定您的 x 接受一个接受任何参数的可调用对象，并且其返回类型为 Any ，例如不管怎样，它是一个通用的可调用对象. x 然后返回与通用相同的内容.

The above specifies that your x takes a callable object that accepts any arguments, and it's return type is Any, e.g. anything goes, it is a generic callable object. x then returns something that is just as generic.

您可以使用 x(f:Callable)->来表达这一点.可通话的:一个普通的 Callable 等效于 Callable [...，Any] .您选择哪一个是样式选择，我在这里使用了明确的选项作为我的个人喜好.

You could express this with x(f: Callable) -> Callable: too; a plain Callable is equivalent to Callable[..., Any]. Which one you pick is a style choice, I used the explicit option here as my personal preference.

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