Python实例化自定义Animal类触发TypeError：birthType()参数数量错误

• 核心触发该TypeError的原因是属性的setter方法定义不符合Python语法要求：Python的setter方法必须接收待赋值的内容作为第二个入参，你当前所有setter都只定义了self参数，当执行self.birthType = birthType这类赋值操作时，Python会自动把self和右侧的赋值内容两个参数传给setter，参数数量不匹配就抛出了该错误。
• 代码还存在其他多处语法&逻辑错误：
  1. appearence属性的setter拼写错误，多写了一个p，命名为apppearence，和属性名不匹配，赋值时无法触发对应setter
  2. setter内部赋值时直接引用了未定义的变量，比如self.__birthType = birthType里的birthType没有作用域来源
  3. __str__方法的最后一个占位符写为{]，方括号和大括号混用会触发格式错误
  4. Mammal类的nurseYoung属性的property、setter以及自定义__str__方法缩进错误，定义在了__init__方法内部，类外部无法访问
  5. Mammal的nurseYoung setter内部直接给公有属性赋值，会递归调用setter自身，引发无限递归崩溃

class Animal:

    def __init__(self, birthType="Unknown", appearence="Unknown", blooded="Unknown"):
        self.birthType = birthType
        self.appearence = appearence
        self.blooded = blooded

    @property
    def birthType(self):
        return self.__birthType

    @birthType.setter
    def birthType(self, value):
        self.__birthType = value

    @property
    def appearence(self):
        return self.__appearence

    @appearence.setter
    def appearence(self, value):
        self.__appearence = value

    @property
    def blooded(self):
        return self.__blooded

    @blooded.setter
    def blooded(self, value):
        self.__blooded = value

    def __str__(self):
        return "A {} is {} it is {} it is {}".format(type(self).__name__, self.birthType, self.appearence, self.blooded)


class Mammal(Animal):

    def __init__(self, birthType="born alive", appearence="hair or fur", blooded="warm blooded", nurseYoung=True):
        super().__init__(birthType, appearence, blooded)
        self.__nurseYoung = nurseYoung

    @property
    def nurseYoung(self):
        return self.__nurseYoung

    @nurseYoung.setter
    def nurseYoung(self, value):
        self.__nurseYoung = value

    def __str__(self):
        return super().__str__() + " and it is {} they nurse their young".format(self.nurseYoung)


class Reptile(Animal):
    def __init__(self, birthType="born in an egg or born alive", appearence="dry scales", blooded="cold blooded"):
        super().__init__(birthType, appearence, blooded)


def main():
    animal1 = Animal("born alive")
    print(animal1.birthType)

if __name__ == "__main__":
    main()

内容的提问来源于stack exchange，提问作者Suhana