python - 使用不带参数的构造函数编写类

Question

属性是存储食品的列表。

这是我以前做过的类(class)食物

class Food(object):
    def __init__(self,name,nutrition,good_until):
        self.name = name
        self.nutrition = nutrition
        self.good_until = good_until
        self.age = 0

方法:

– 构造函数不接受任何参数。

– get_stock_names():返回代表股票名称的字符串列表库存中的所有食品。

– load(food):将食物对象添加到库存中。

class VendingMachine(object):
    def load(self,food):
        self.food = food
        return self.food
    def get_stock_names(self):
        self.obj = []
        self.obj.append(self.load())


machine = VendingMachine()
apple = Food("apple", 70, 7)
banana = Food("banana", 100, 4)
yoghurt = FermentedFood("yoghurt", 50, 0, 10)
machine.load(banana)
machine.load(apple)
machine.load(yoghurt)
machine.load(apple)
print(machine.get_stock_names())  

我应该得到[“香蕉”，“苹果”，“酸奶”，“苹果”]

哪一部分是错误的？？？

Answer 1

您仍然应该有一个 __init__ 方法来初始化变量，如下所示:

class VendingMachine(object):
    def __init__(self):
        self.foods = []

    def load(self,food):
        self.foods.append(food)
        return self.foods

    def get_stock_names(self):
        return [i.name for i in self.foods]

machine = VendingMachine()
apple = Food("apple", 70, 7)
banana = Food("banana", 100, 4)
yoghurt = FermentedFood("yoghurt", 50, 0, 10)
machine.load(banana)
machine.load(apple)
machine.load(yoghurt)
machine.load(apple)
print(machine.get_stock_names())
["banana", "apple", "yoghurt", "apple"]