我们如何通过扩展类将 Python 中的抽象方法和自定义异常结合起来？

编程问答 2022-05-16

问题描述

有没有好的方法使用abstractmethod？我担心人们仍然可以实例化 class InvalidRequestError 的对象，但我没想到会发生这种情况？

场景 - 1

from http import HTTPStatus
from abc import ABC,abstractmethod

class BaseError(ABC,Exception): # Is it a good idea to subclass the Exception's class as well ?
    pass

class RequestError(BaseError,ABC):
    @abstractmethod
    def STATUS_CODE(self):
        raise NotImplementedError

class InvalidRequestError(RequestError):
    STATUS_CODE = HTTPStatus.BAD_REQUEST

# InvalidRequestError() # I was expecting it to raise an error but it didn't.

场景 - 2

from http import HTTPStatus
from abc import ABC,abstractmethod

class BaseError(ABC):
    pass

class RequestError(BaseError,ABC):
    @abstractmethod
    def STATUS_CODE(self):
        raise NotImplementedError

class InvalidRequestError(RequestError):
    STATUS_CODE = HTTPStatus.BAD_REQUEST
InvalidRequestError() # runs

但这如我所料，（它引发了追溯）


import abc

class BaseError(abc.ABC):
    pass

class GeneralError(BaseError):

    @abc.abstractmethod
    def something(self):
        raise NotImplementedError

class Test(GeneralError):
    pass

# test() # raises the exception I was looking for; TypeError: Can't instantiate abstract class Test with abstract methods...

# And so does the below,from http import HTTPStatus
from abc import ABC,ABC):
    @abstractmethod
    def STATUS_CODE(self):
        raise NotImplementedError

class InvalidRequestError(RequestError):
    pass # STATUS_CODE = HTTPStatus.BAD_REQUEST

# InvalidRequestError() # raises the exception I was looking for; TypeError: Can't instantiate abstract class Test with abstract methods.

与最上面的代码片段相比，在最后一个片段中，我所做的更改不再是继承 Exceptions 类并用 pass 替换 STATUS_CODE 行。

我想了解为什么会发生这种情况以及实现这一目标的更pythonic的方法是什么？

感谢路过；

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