Inheritance in python, Attribute error -

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• what meaning of single- , double-underscore before object name? 11 answers

i have started learning python , having hard time how inheritance works in python.

i have created 2 classes, 1 named animal , 1 named dog. dog class inherits animal class. have attributes name, height, sound etc in animal class want use in dog class. setting attributes using init method of animal class.

class animal:     __name = ""     __height = 0     __weight = 0     __sound = 0      def __init__(self, name, height, weight, sound):         self.__name = name         self.__height = height         self.__wight = weight         self.__sound = sound      def set_name(self, name):         self.__name = name      def get_name(self):         return self.__name      def set_height(self, height):         self.__height = height      def get_height(self):         return self.__height      def set_weight(self, weight):         self.__weight = weight      def get_weight(self):         return self.__weight      def set_sound(self, sound):         self.__sound = sound      def get_sound(self):         return self.__sound      def get_type(self):         print("animal")      def tostring(self):         return "{} {} cm tall , {} kilograms , says {}".format(self.__name,                                                                       self.__height,                                                                       self.__weight,                                                                       self.__sound)   cat = animal("whiskers", 50, 20, "meow") print(cat.tostring())   class dog(animal):     __owner = none      def __init__(self, name, height, weight, sound, owner):         super(dog, self).__init__(name, height, weight, sound)         self.__owner = owner      def set_owner(self, owner):         self.__owner = owner      def get_owner(self):         return self.__owner      def get_type(self):         print("dog")      def tostring(self):         return '{} {} cm tall , {} kilograms , says {} owner {}'.format(self.__name,                                                                                       self.__height,                                                                                       self.__weight,                                                                                       self.__sound,                                                                                       self.__owner)      def multiple_sounds(self, how_many=none):         if how_many none:             print(self.get_sound())         else:             print(self.get_sound() * how_many) my_dog = dog("spot", 50, 40, "ruff", "derek") print(my_dog.tostring()) 

problem when try print attributes using object of dog class, error displayed saying "

*line 73, in tostring     return '{} {} cm tall , {} kilograms , says {} owner {}'.format(self.__name, attributeerror: 'dog' object has no attribute '_dog__name'*  

can me find problem in code ?

members start double underscore sort of private, not accessible cild classes. should use single underscore. python not use implicit access specifiers c++ or java instead special name convention used: names _ prefix protected , names __ private. python not check don't violate convention, considered bad practice access protected or private methods outside of class. if start name double underscore mangled in special way. __name becomes _animal__name when use in animal class , _dog__name when use in dog.