描述符的应用

class Typed:
    def __init__(self,key,expected_type):
        self.key=key
        self.expected_type=expected_type
    def __get__(self, instance, owner):
        print('get方法')
        return instance.__dict__[self.key]
    def __set__(self, instance, value):
        print('set方法')
        if not isinstance(value,self.expected_type):
            raise TypeError('%s 传入的类型不是%s' %(self.key,self.expected_type))
        instance.__dict__[self.key]=value
    def __delete__(self, instance):
        print('delete方法')
        instance.__dict__.pop(self.key)

class People:
    name=Typed('name',str) #t1.__set__()  self.__set__()
    age=Typed('age',int) #t1.__set__()  self.__set__()
    def __init__(self,name,age,salary):
        self.name=name
        self.age=age
        self.salary=salary

# p1=People('alex','13',13.3)
p1=People(213,13,13.3)