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,我创建了一个基础抽象类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
.
然后我创建了一个 Base
的子类,称为 Base_1
,它旨在提供一些功能,但仍然是抽象的.Base_1
中没有 name
属性,但是 python 会在没有错误的情况下设置该类的对象.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
自从 Python 3.3 修复了一个错误,这意味着 property()
装饰器现在在应用于抽象方法时可以正确识别为抽象.
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:顺序很重要,你必须在@abstractmethod
Note: Order matters, you have to use @property
above @abstractmethod
Python 3.3+:(python文档):
from abc import ABC, abstractmethod
class C(ABC):
@property
@abstractmethod
def my_abstract_property(self):
...
Python 2:(python 文档)
from abc import ABC, abstractproperty
class C(ABC):
@abstractproperty
def my_abstract_property(self):
...
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