描述符简单应用示例

Posted 2021-02-05 sun-10387834

 1 #Author : Kelvin
 2 #Date : 2019/1/24 20:57
 3 
 4 #实现目标：控制类的实例化对象时传入的参数值
 5 
 6 #定义描述符
 7 class Type():
 8     def __init__(self,key,type):
 9         self.key=key
10         self.type=type
11     def __get__(self, instance, owner):
12         # print("get")
13         return instance.__dict__[self.key]
14     def __set__(self, instance, value):
15         # print("set")
16         if not isinstance(value,self.type):
17             raise TypeError("%s Type is not %s"%(self.key,self.type))
18         instance.__dict__[self.key]=value
19     def __delete__(self, instance):
20         # print("delete")
21         instance.__dict__.pop(self.key)
22 
23 #定义类
24 class People:
25     name=Type("name",str)
26     age=Type("age",int)
27     salary=Type("salary",float)
28     def __init__(self,name,age,salary):
29         self.name=name
30         self.age=age
31         self.salary=salary
32 p1=People("kelvin",18,12800.36)

此时如果实例化对象时，传入的参数不符合条件就会抛出异常！