class User:
    def __init__(self, name, hobby=[]):
        self.name = name
        self.hobby = hobby

    def add_hobby(self, hobby):
        self.hobby.append(hobby)

    def remove_hobby(self, hobby):
        self.hobby.remove(hobby)

    def __str__(self):
        return self.name + ',' + '-'.join(self.hobby)


if __name__ == '__main__':
    u1 = User('小明')
    u1.add_hobby('足球')
    print(u1)  #小明,足球
    print(id(u1.hobby))  # 2074461954696

    u2 = User('小强')
    u2.add_hobby('美女')
    print(u2)  #小强,足球-美女
    print(u1)  #小明,足球-美女
    print(id(u2.hobby))  # 2074461954696