python super( )method疑问

Question

疑问在这段代码的注释里

class Dog:
    kennel = 0
    def __init__(self, breed):
        self.breed = breed
        Dog.kennel += 1
    def __str__(self):
        return self.breed + " says: Woof!"


class SheepDog(Dog):
    def __str__(self):
        return super().__str__() + " Don't run away, Little Lamb!"
class LowlandDog(SheepDog):
    def __str__(self):
        return Dog.__str__(self) + " I don't like mountains!"#这里用到Dog class的时候为什么要加self，其他像super().__str__()这种就不用加?
class GuardDog(Dog):
    def __str__(self):
        return super().__str__() + " Stay where you are, Mister Intruder!"


rocky = LowlandDog("Collie")
luna = GuardDog("Dobermann")
print(rocky.kennel)                           #这里的ouput是2，但我觉得是1，有点不太明白?
print(rocky)

Answer 1

因为super()里隐式传了self，类方法里就不用再传了
kennel是Dog类属性，并不属于某个实例，任何一个实例都可以修改和访问。所以当实例rocky的时候，kennel变成1，再实例luna的时候，kennel就变成了2。