在子类中强制类变量

抽象基类允许声明一个属性抽象，这将强制所有实现类都具有该属性。我仅出于完整性的目的提供此示例，许多pythonista人士认为您提出的解决方案更具pythonic的功能。

import abcclass base(object):    __metaclass__ = abc.ABCmeta    @abc.abstractproperty    def value(self):        return 'Should never get here'class Implementation1(base):    @property    def value(self):        return 'concrete property'class Implementation2(base):    pass # doesn't have the required property

试图实例化第一个实现类：

print Implementation1()Out[6]: <__main__.Implementation1 at 0x105c41d90>

试图实例化第二个实现类：

print Implementation2()---------------------------------------------------------------------------TypeErrorTraceback (most recent call last)<ipython-input-4-bbaeae6b17a6> in <module>()----> 1 Implementation2()TypeError: Can't instantiate abstract class Implementation2 with abstract methods value