定义 types.Dict 和 dict 之间的区别？

我正在练习使用 Python 3.5 中的类型提示。我的一位同事使用typing.Dict:

import typing


def change_bandwidths(new_bandwidths: typing.Dict,
                      user_id: int,
                      user_name: str) -> bool:
    print(new_bandwidths, user_id, user_name)
    return False


def my_change_bandwidths(new_bandwidths: dict,
                         user_id: int,
                         user_name: str) ->bool:
    print(new_bandwidths, user_id, user_name)
    return True


def main():
    my_id, my_name = 23, "Tiras"
    simple_dict = {"Hello": "Moon"}
    change_bandwidths(simple_dict, my_id, my_name)
    new_dict = {"new": "energy source"}
    my_change_bandwidths(new_dict, my_id, my_name)

if __name__ == "__main__":
    main()

两者都工作得很好，看起来没有什么区别。

我已阅读typing模块文档 https://docs.python.org/3/library/typing.html.

Between typing.Dict or dict我应该在程序中使用哪一个？

使用普通的之间没有真正的区别typing.Dict and dict, no.

However, typing.Dict is a Generic type https://docs.python.org/3/library/typing.html#generics ^* that lets you specify the type of the keys and values too, making it more flexible:

def change_bandwidths(new_bandwidths: typing.Dict[str, str],
                      user_id: int,
                      user_name: str) -> bool:

因此，很可能在项目生命周期的某个时刻，您想要更精确地定义字典参数，此时扩展typing.Dict to typing.Dict[key_type, value_type]是比替换“更小的”变化dict.

您可以使用以下方法使其更加通用Mapping https://docs.python.org/3/library/typing.html#typing.Mapping or MutableMapping https://docs.python.org/3/library/typing.html#typing.MutableMapping在这里输入；因为你的函数不需要alter映射，我会坚持Mapping. A dict是一种映射，但您可以创建也满足映射接口的其他对象，并且您的函数很可能仍然可以使用这些对象：

def change_bandwidths(new_bandwidths: typing.Mapping[str, str],
                      user_id: int,
                      user_name: str) -> bool:

现在你清楚地告诉这个函数的其他用户你的代码实际上不会alter the new_bandwidths映射传入。

您的实际实现只是期望一个可打印的对象。这可能是一个测试实现，但就目前情况而言，如果您使用，您的代码将继续工作new_bandwidths: typing.Any，因为Python中的任何对象都是可打印的。

^*: Note: If you are using Python 3.7 or newer, you can use dict as a generic type if you start your module with from __future__ import annotations https://www.python.org/dev/peps/pep-0563/, and as of Python 3.9, dict (as well as other standard containers) supports being used as generic type even without that directive https://www.python.org/dev/peps/pep-0585/.