使用 mypy 时在 python 中正确键入 exceptions/errors 的元组

Question

我已经编写了自己的装饰器 add_warning 以便在发生某些错误时打印自定义错误消息。装饰器接受一条消息和打印该消息的错误类型。我还想为这个装饰器添加类型并使用 mypy 检查它。这在我使用 Type[Exception] 时只是抛出普通 Exception 的情况下效果很好。但是，mypy 在我使用 OSError 或 AttributeError 等其他错误时抱怨说：

error: Argument "errors" to "add_warning" has incompatible type "Tuple[Type[OSError], Type[AttributeError]]"; expected "Union[str, Type[Exception], Tuple[Type[Any]]]".

有人知道是否有比在这里使用 Any 或 Tuple[Type[OSError], Type[AttributeError]] 更好的方法吗？具体来说，所有 Python 错误是否有更通用的类型？

下面是代码：

from functools import wraps
from typing import Union, Tuple, Callable, Type


def add_warning(message: str, flag: str = 'Info',
                errors: Union[str, Type[Exception], Tuple[Type[Exception]]] = 'all') -> Callable:
    """
    Add a warning message to a function, when certain error types occur.
    """
    if errors == 'all':
        errors = Exception

    def decorate(func: Callable):
        @wraps(func)
        def wrapper(*args, **kwargs):
            try:
                result = func(*args, **kwargs)
            except errors:
                warn(message, flag)
                return []
            else:
                return result
        return wrapper
    return decorate


def warn(message: str, flag: str = 'Info') -> None:
    """Print the colored warning message."""
    print(f"{flag}: {message}")


if __name__ == '__main__':

    @add_warning('This is another test warning.', flag='Error')
    def test_func1():
        raise Exception

    @add_warning('This is a test warning.', flag='Error', errors=(OSError, AttributeError))
    def test_func2():
        raise OSError

    test_func1()
    test_func2()

Answer 1

问题是 Tuple[Type[Exception] 表示具有单个值的元组。你想要一个可变大小的元组，所以使用省略号：Tuple[Type[Exception], ...] 下面的工作没有 mypy 抱怨：

from functools import wraps
from typing import Union, Tuple, Callable, Type


def add_warning(message: str, flag: str = 'Info',
                errors: Union[str, Type[Exception], Tuple[Type[Exception], ...]] = 'all') -> Callable:
    """
    Add a warning message to a function, when certain error types occur.
    """
    if errors == 'all':
        errors = Exception

    def decorate(func: Callable):
        @wraps(func)
        def wrapper(*args, **kwargs):
            try:
                result = func(*args, **kwargs)
            except errors:
                warn(message, flag)
                return []
            else:
                return result
        return wrapper
    return decorate


def warn(message: str, flag: str = 'Info') -> None:
    """Print the colored warning message."""
    print(f"{flag}: {message}")


if __name__ == '__main__':

    @add_warning('This is another test warning.', flag='Error')
    def test_func1():
        raise Exception

    @add_warning('This is a test warning.', flag='Error', errors=(OSError, AttributeError))
    def test_func2():
        raise OSError

    test_func1()
    test_func2()

使用 mypy 时在 python 中正确键入 exceptions/errors 的元组

Correct typing of tuple of exceptions/errors in python when using mypy

python

exception

type-hinting

python-3.x

mypy