Python 对象装饰器

# 利用对象装饰器和描述符组合来限定类实例属性的类型


class Typed:
    def __init__(self,key,type):
        self.key=key
        self.type=type

    def __get__(self, instance, owner):
        print(‘__get__‘)
        return instance.__dict__[self.key]

    def __set__(self, instance, value):
        print(‘__set__‘)
        if type(value) is self.type:
            instance.__dict__[self.key]=value
        else:
            raise TypeError(‘属性【%s】的类型必须是%s‘%(self.key,self.type))


    def __delete__(self, instance):
        print(‘__delete__‘)
        del instance.__dict__[self.key]

def method(**kwargs):
    def wrapper(obj):
        for key,value in kwargs.items():
            setattr(obj,key,Typed(key,value)) # 利用装饰器将描述符设置到类里面
        return obj
    return wrapper



@method(x=str,y=int)
class Foo:
    def __init__(self,x,y):
        self.x=x
        self.y=y

f=Foo(‘jack‘,23)
print(f.__dict__)