python父类继承中缺少位置参数？

Question

在学习父类继承中，调用子类的方法显示missing 1 required positional argument:
代码如下：

# 以上是父类
class IceCreamStand(Restaurant):
    """冰激凌"""
    def __init__(self, restaurant_name, cuisine_type):
        """初始化父类属性"""
        super().__init__(restaurant_name, cuisine_type)
        self.flavors = ['a','b']
    def describe_flavors(self, flavors):
        print('We have following flavors:')
        for flavor in flavors:
            print(f'-{flavor}')
my_icecreamstand = IceCreamStand('蜜雪冰城','奶茶')
my_icecreamstand.describe_flavors()

这是从《到实践中》练习9-6的题
显示结果为：

Traceback (most recent call last):
File "D:\Sublime Text\restaurant.py", line 39, in
print(my_icecreamstand.describe_flavors())
TypeError: describe_flavors() missing 1 required positional argument: 'flavors'

Answer 1

因为你的describe_flavors方法中，for flavor in flavors循环 这一句，flavors参数不是IceCreamStand类的属性flavors，而是调用方法时传入的参数
应该改成

    def describe_flavors(self):
        print('We have following flavors:')
        for flavor in self.flavors:
            print(f'-{flavor}')

Answer 2

 def describe_flavors(self, flavors=self.flavors):

试试这样

Answer 3

子类属性添加了，也实例化了，不知道为什么