python - Python中的抽象属性

Question

这个问题在这里已经有了答案:

How to create abstract properties in python abstract classes (5 个回答)

关闭 2年前。

在 Python 中用抽象属性实现以下 Scala 代码的最短/最优雅的方法是什么？

abstract class Controller {

    val path: String

}

Controller 的子类被 Scala 编译器强制定义“路径”。子类如下所示:

class MyController extends Controller {

    override val path = "/home"

}

Answer 1

Python 3.3+

from abc import ABCMeta, abstractmethod


class A(metaclass=ABCMeta):
    def __init__(self):
        # ...
        pass

    @property
    @abstractmethod
    def a(self):
        pass

    @abstractmethod
    def b(self):
        pass


class B(A):
    a = 1

    def b(self):
        pass

未能在派生类B中声明a或b会引发TypeError如:

TypeError: Can't instantiate abstract class B with abstract methods a

Python 2.7

有一个 @abstractproperty装饰器:

from abc import ABCMeta, abstractmethod, abstractproperty


class A:
    __metaclass__ = ABCMeta

    def __init__(self):
        # ...
        pass

    @abstractproperty
    def a(self):
        pass

    @abstractmethod
    def b(self):
        pass


class B(A):
    a = 1

    def b(self):
        pass