我应该提高对在Python坏/非法参数组合哪个异常？ [英] Which exception should I raise on bad/illegal argument combinations in Python?

问题描述

我想知道指示在Python无效的参数组合的最佳实践。我已经遇到，你有一个函数像这样一些情况：

I was wondering about the best practices for indicating invalid argument combinations in Python. I've come across a few situations where you have a function like so:

def import_to_orm(name, save=False, recurse=False):
    """
    :param name: Name of some external entity to import.
    :param save: Save the ORM object before returning.
    :param recurse: Attempt to import associated objects as well. Because you
        need the original object to have a key to relate to, save must be
        `True` for recurse to be `True`.
    :raise BadValueError: If `recurse and not save`.
    :return: The ORM object.
    """
    pass

这个唯一的烦恼是，每个包都有自己的，平时略有不同 BadValueError 。我知道，在Java中存在 java.lang.IllegalArgumentException异常 - 这是很好理解，每个人都将是创建他们自己的 BadValueError S IN Python或有另一种，preferred方法？

The only annoyance with this is that every package has its own, usually slightly differing BadValueError. I know that in Java there exists java.lang.IllegalArgumentException -- is it well understood that everybody will be creating their own BadValueErrors in Python or is there another, preferred method?

推荐答案

我只想养的 ValueError错误，除非你需要一个更具体的异常。

I would just raise ValueError, unless you need a more specific exception..

def import_to_orm(name, save=False, recurse=False):
    if recurse and not save:
        raise ValueError("save must be True if recurse is True")

有真的这样做没有意义的类BadValueError（ValueError错误）：通过 - 自定义类是在使用中的 ValueError错误，为什么不能使用？

There's really no point in doing class BadValueError(ValueError):pass - your custom class is identical in use to ValueError, so why not use that?

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