如何在python抽象类中创建抽象属性 [英] How to create abstract properties in python abstract classes

问题描述

在下面的代码中，我创建一个基本抽象类 Base 。我希望从 Base 继承的所有类都提供 name 属性，因此我将此属性设置为 @abstractmethod 。

In the following code, I create a base abstract class Base. I want all the classes that inherit from Base to provide the name property, so I made this property an @abstractmethod.

然后我创建了 Base 的子类。 Base_1 ，旨在提供某些功能，但仍保持抽象。 Base_1 中没有 name 属性，但是python实例化了该类的对象而没有错误。如何创建抽象属性？

Then I created a subclass of Base, called Base_1, which is meant to supply some functionality, but still remain abstract. There is no name property in Base_1, but nevertheless python instatinates an object of that class without an error. How does one create abstract properties?

from abc import ABCMeta, abstractmethod
class Base(object):
    __metaclass__ = ABCMeta
    def __init__(self, strDirConfig):
        self.strDirConfig = strDirConfig

    @abstractmethod
    def _doStuff(self, signals):
        pass

    @property    
    @abstractmethod
    def name(self):
        #this property will be supplied by the inheriting classes
        #individually
        pass


class Base_1(Base):
    __metaclass__ = ABCMeta
    # this class does not provide the name property, should raise an error
    def __init__(self, strDirConfig):
        super(Base_1, self).__init__(strDirConfig)

    def _doStuff(self, signals):
        print 'Base_1 does stuff'


class C(Base_1):
    @property
    def name(self):
        return 'class C'


if __name__ == '__main__':
    b1 = Base_1('abc')  

推荐答案

自 Python 3.3 以来，已修复一个错误意味着 property（）装饰器现在可以正确地识别为抽象，应用于抽象方法。

Since Python 3.3 a bug was fixed meaning the property() decorator is now correctly identified as abstract when applied to an abstract method.

注意：订购问题，必须在 @抽象方法

Note: Order matters, you have to use @property before @abstractmethod

Python 3.3 +：（ python docs ）：

class C(ABC):
    @property
    @abstractmethod
    def my_abstract_property(self):
        ...

Python 2：（ Python文档）

class C(ABC):
    @abstractproperty
    def my_abstract_property(self):
        ...

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