Question

在python中继承时，我得到了私有变量跟随错误：

AttributeError：'dog'对象没有属性'_dog__name'

我搜索了很多，但不明白我的问题在哪里;

class animal(object):
    __name = ""
    __height = ""
    __weight = ""
    __sound = ""

    def __init__(self, name, height, weight, sound):
        self.__name = name
        self.__height = height
        self.__weight = weight
        self.__sound = sound


    def toString(self):
        return "{} is {} cm and {} weight and say {}.".format(self.__name, self.__height, self.__weight, self.__sound)

class dog(animal):
    __owner = ""

    def __init__(self, name, height, weight, sound, owner):
        self.__owner = owner
        super(dog, self).__init__(name, height, weight, sound)

    def toString(self):
        return "{} is {} cm and {} weight and say {} and belongs to {}.".format(self.__name, self.__height,
                                                                                self.__weight, self.__sound,
                                                                                self.__owner)

puppy = dog('puppy', 45, 15, 'bark', 'alex')

puppy.toString()

Answer 1

当您使用双下划线创建var时，它只是用于将其指示为私有变量的符号，python会对变量名本身进行名称修改，以防止以正常方式访问它。

然而，它仍然不是真正的私有变量，如C / C ++。你仍然可以访问所谓的python“private var”，其语法如下

var = __myvar
# access with _<class name>__myvar

来自PEP，

_single_leading_underscore：弱“内部使用”指标。例如。来自M import *不会导入名称以。开头的对象下划线。
__ double_leading_underscore：在命名一个类属性时，调用名称重整（在类FooBar中，__ boo变成_FooBar__boo

对于你的情况，将你的dog class toString方法更改为下面然后它应该可以

def toString(self):
    return "{} is {} cm and {} weight and say {} and belongs to {}.".format(self._animal__name, self._animal__height,
                                                                                self._animal__weight, self._animal__sound,
                                                                                self.__owner) # __owner remains because its not inherit from class animal

另一种选择是将动物类变量更改为单个下划线_，如果你真的不需要双下划线__

在python中继承私有变量

1 个答案: