相当于 Python 中字段的 NotImplementedError [英] Equivalent of NotImplementedError for fields in Python

问题描述

在 Python 2.x 中，当您想将方法标记为抽象方法时，您可以像这样定义它:

In Python 2.x when you want to mark a method as abstract, you can define it like so:

class Base:
    def foo(self):
        raise NotImplementedError("Subclasses should implement this!")

然后如果你忘记覆盖它，你会得到一个很好的提醒异常.是否有等效的方法将字段标记为抽象?或者你只能在类文档字符串中说明它?

Then if you forget to override it, you get a nice reminder exception. Is there an equivalent way to mark a field as abstract? Or is stating it in the class docstring all you can do?

起初我以为我可以将字段设置为 NotImplemented，但是当我查看它的实际用途(丰富的比较)时，它似乎是滥用.

At first I thought I could set the field to NotImplemented, but when I looked up what it's actually for (rich comparisons) it seemed abusive.

推荐答案

是的，你可以.使用 @property 装饰器.例如，如果您有一个名为example"的字段，那么您不能这样做:

Yes, you can. Use the @property decorator. For instance, if you have a field called "example" then can't you do something like this:

class Base(object):

    @property
    def example(self):
        raise NotImplementedError("Subclasses should implement this!")

运行以下代码会产生一个 NotImplementedError，就像你想要的那样.

Running the following produces a NotImplementedError just like you want.

b = Base()
print b.example

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