Python3基础-类的装饰器

函数的装饰器

#函数的装饰器
def deco(func):
    print("deco======")
    return func

@deco  #test = deco(test)
def test():
    print("test=====")

test()
"""
执行结果：
deco======
test=====
"""

一切皆对象

eg:

#一切皆对象
def test():
    print("-----test----")

test.x =1
test.y =2
print(test.__dict__)

以上代码执行结果如下：

{'x': 1, 'y': 2}

类的装饰器

#类的装饰器
def deco(obj):
    print("deco======",obj)  #输出的是 deco====== <class '__main__.test'>
    obj.x = 1  #添加test的类的数字属性
    obj.y = 2  #添加test的类的数字属性
    return obj

@deco  #test = deco(test)
class test:
    def __init__(self,name):
        self.name = name

    def testFunc(self):
        print("======",self.name)


print(test)  #输出的是  <class '__main__.test'>
print(test.__dict__)
"""
执行结果：
deco====== <class '__main__.test'>
<class '__main__.test'>
{'__module__': '__main__', '__init__': <function test.__init__ at 0x0307F6A8>, 'testFunc': <function test.testFunc at 0x0307F780>, '__dict__': <attribute '__dict__' of 'test' objects>, '__weakref__': <attribute '__weakref__' of 'test' objects>, '__doc__': None, 'x': 1, 'y': 2}
"""

因为obj.x =1 obj.y =2 固定写死了，如何灵活运用

def tesDeco(**kwargs):
    def deco(obj):
        # print("deco======",obj)  #输出的是 deco====== <class '__main__.test'>
        # print("kwargs",kwargs)
        for key,value in kwargs.items():
            # print(key,value)
            setattr(obj,key,value)
        return obj
    print("====kwargs",kwargs)
    return deco

@tesDeco(a=1,b=2)  #tesDeco(x=1,y=2)-->deco  @deco   test = deco(test)
class test:
    def __init__(self,name):
        self.name = name

    def testFunc(self):
        print("======",self.name)
print(test.__dict__)

以上代码执行结果如下：

====kwargs {'a': 1, 'b': 2}
{'__module__': '__main__', '__init__': <function test.__init__ at 0x0110F780>, 'testFunc': <function test.testFunc at 0x0110F7C8>, '__dict__': <attribute '__dict__' of 'test' objects>, '__weakref__': <attribute '__weakref__' of 'test' objects>, '__doc__': None, 'a': 1, 'b': 2}

在循环读取kwargs.items()时

错误 eg1

def tesDeco(**kwargs):
    def deco(obj):
        # print("deco======",obj)  #输出的是 deco====== <class '__main__.test'>
        # print("kwargs",kwargs)
        for key,value in kwargs.items():
            obj.__dict__[key]=value  #不允许这样写，会报错TypeError: 'mappingproxy' object does not support item assignment
        return obj
    print("====kwargs",kwargs)
    return deco

错误 eg2

def tesDeco(**kwargs):
    def deco(obj):
        # print("deco======",obj)  #输出的是 deco====== <class '__main__.test'>
        # print("kwargs",kwargs)
        for key,value in kwargs.items():
            obj.key =value  # 最后写入类属性的是{'key':2}
        return obj
    print("====kwargs",kwargs)
    return deco

 类的装饰器的应用

class Desc():
    def __init__(self,key,expected_type):
        self.key = key
        self.expected_type = expected_type

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

    def __set__(self, instance, value):
        print("__set__")
        if not isinstance(value,self.expected_type):
            raise TypeError("%s 类型必须输入%s类型"%(self.key,self.expected_type))
        instance.__dict__[self.key]=value  #写入

    def __delete__(self, instance):
        print("__delete__")
        instance.__dict__.pop(self.key)

def tesDeco(**kwargs):
    def deco(obj):
        # print("deco======",obj)  #输出的是 deco====== <class '__main__.test'>
        # print("kwargs",kwargs)
        for key,value in kwargs.items():
            print('===',key,value)
            setattr(obj,key,Desc(key,value))  #新增people的属性  ==》name = Desc('name',str)

        return obj
    print("====kwargs",kwargs)
    return deco
@tesDeco(name=str,age=int)
class People():
     # name = Desc('name',str)
     # age = Desc('age',int)
     def __init__(self,name,age,salary):
         self.name = name
         self.age = age
         self.salary = salary

print(People.__dict__)
p1 = People('su',30,100)