Python的super（），抽象基类和NotImplementedError [英] Python's super(), abstract base classes, and NotImplementedError

问题描述

抽象基类在Python中仍然很方便。在编写一个抽象基类，我希望每个子类都具有一个 spam（）方法，我想编写如下代码：

Abstract base classes can still be handy in Python. In writing an abstract base class where I want every subclass to have, say, a spam() method, I want to write something like this:

class Abstract(object):
    def spam(self):
        raise NotImplementedError

挑战也来自于想要使用 super（）并通过包含它来正确完成在整个子类链中。在这种情况下，似乎我必须包装每个 super 调用，如下所示：

The challenge comes in also wanting to use super(), and to do it properly by including it in the entire chain of subclasses. In this case, it seems I have to wrap every super call like the following:

class Useful(Abstract):
    def spam(self):
        try:
            super(Useful, self).spam()
        except NotImplementedError, e:
            pass
        print("It's okay.")

简单就可以了子类，但是在编写具有许多方法的类时，尝试除外的操作会变得有些麻烦和丑陋。有没有从抽象基类继承的更优雅的方式？我只是做错了吗？

That's okay for a simple subclass, but when writing a class that has many methods, the try-except thing gets a bit cumbersome, and a bit ugly. Is there a more elegant way of subclassing from abstract base classes? Am I just Doing It Wrong?

推荐答案

您可以在python 2.6+中使用 abc模块：

You can do this cleanly in python 2.6+ with the abc module:

import abc
class B(object):
    __metaclass__ = abc.ABCMeta
    @abc.abstractmethod
    def foo(self):
        print 'In B'

class C(B):
    def foo(self):
        super(C, self).foo()
        print 'In C'

C().foo()

输出将为

In B
In C

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