为什么我定义的“狗”类的“步行”方法不被“牛头犬”或“罗素梗”子类继承？

Question

在我的最后一行代码中，当我调用'walk()‘方法时，什么都不会发生。但是当我在控制台中运行它时，我会得到一个错误：

回溯(最近一次调用)：File ""，第2行，在AttributeError中：‘Bull犬类’对象没有属性‘has’

class Pets:

    def __init__(self,dogs):
        self.dogs=dogs


class Dog:

    # Class attribute
    species = 'mammal'

    # Initializer / Instance attributes
    def __init__(self, name, age):
        self.name = name
        self.age = age
        self.is_hungry = True

# instance method
    def eat(self):
        self.is_hungry = False

#Walk instance method
    def walk(self):
        return "{} is walking!" .format(self.name)

# Child class (inherits from Dog class)
class RussellTerrier(Dog):
    def run(self, speed):
        return "{} runs {}".format(self.name, speed)

# Child class (inherits from Dog class)
class Bulldog(Dog):
    def run(self, speed):
        return "{} runs {}".format(self.name, speed)

# create isntances of dogs
my_dogs = [
    Bulldog("Tom", 6),
    RussellTerrier("Fletcher", 7),
    Dog("Larry", 9)
]

my_Pets=Pets(my_dogs)

#walking

for doggy in my_Pets.dogs:
    doggy.walk()

Answer 1

您的walk方法正在返回一个string。如果您期望它打印字符串，那么您需要显式地这样做。最后两行应该是：

for doggy in my_Pets.dogs:
    print(doggy.walk())

AttributeError的问题很可能是复制粘贴到控制台的方式。