Python面向对象编程Day 28部分

 1 class Typed:
 2     def __init__(self,key,expected_type):
 3         self.key=key
 4         self.expected_type=expected_type
 5     def __get__(self, instance, owner): #instance是p1实例
 6         print('get方法')
 7         return instance.__dict__[self.key]
 8     def __set__(self, instance, value):
 9         print('set方法')
10         if not isinstance(value,self.expected_type):
11             raise TypeError('%s 传入的类型不是%s' %(self.key,self.expected_type))
12         instance.__dict__[self.key]=value
13     def __delete__(self, instance):
14         print('delete方法')
15         instance.__dict__.pop(self.key)
16 
17 class People:
18     name=Typed('name',str) #t1.__set__()  self.__set__()
19     age=Typed('age',int) #t1.__set__()  self.__set__()
20     def __init__(self,name,age,salary):
21         self.name=name
22         self.age=age
23         self.salary=salary
24 
25 p1=People(213,13,13.3)

 1 def deco(obj):
 2     print('==========',obj)
 3     obj.x=1
 4     obj.y=2
 5     obj.z=3
 6     return obj
 7 
 8 @deco #Foo=deco(Foo)
 9 class Foo:
10     pass
11 
12 print(Foo.__dict__)

 1 class Lazyproperty:
 2     def __init__(self,func):
 3         # print('==========>',func)
 4         self.func=func
 5     def __get__(self, instance, owner):
 6         print('get')
 7         if instance is None:
 8             return self
 9         res=self.func(instance) #函数运行的时候要把实例本身传进去，而不是类
10         setattr(instance,self.func.__name__,res)
11         return res
12     # def __set__(self, instance, value):　　
13     #     pass
14 
15 class Room:
16     def __init__(self,name,width,length):
17         self.name=name
18         self.width=width
19         self.length=length
20     @Lazyproperty  # area=Lazypropery(area)
21     def area(self):
22         return self.width * self.length
23     @property  # area1=property(area1)
24     def area1(self):
25         return  self.width * self.length
26 
27 r1=Room('厕所',1,1)
28 print(r1.__dict__)
29 
30 # 实例调用
31 print(r1.area)
32 print(r1.__dict__)
33 print(Room.__dict__)
34 
35 # 类调用    被描述符代理的属性 instance传的是None owner不变
36 print(Room.area)
37 
38 # 不再调用get方法，因为此时有实例属性，
39 # 其优先级高于非数据描述符 若此时加上set属性就无法实现了
40 print(r1.area)
41 print(r1.area)

 1 class Foo:
 2     @property
 3     def AAA(self):
 4         print('get的时候运行我啊')
 5 
 6     # 下面两个函数依附于静态属性存在
 7     @AAA.setter
 8     def AAA(self,val):
 9         print('set的时候运行我啊',val)
10     @AAA.deleter
11     def AAA(self):
12         print('del的时候运行我啊')
13 #只有在属性AAA定义property后才能定义AAA.setter,AAA.deleter
14 f1=Foo()
15 f1.AAA
16 f1.AAA='aaa'
17 del f1.AAA

#另一种写法，效果一样

class Foo:

    def get_AAA(self):
        print('get的时候运行我啊')
    def set_AAA(self,val):
        print('set的时候运行我啊',val)
    def del_AAA(self):
        print('del的时候运行我啊')

    AAA=property(get_AAA,set_AAA,del_AAA)　　#顺序不要变
f1=Foo()
f1.AAA
f1.AAA='aaa'
del f1.AAA

1 def say_hi(name):
2     return('hello,%s'%name)
3 FFo=type('FFo',(object,),{'gender':'female','say_hi':say_hi})
4 print(FFo)
5 print(FFo.__dict__)
6 print(FFo.say_hi('chenyuan'))
7 print('Your gender is %s'%FFo.gender)

 1 class MyType(type):
 2     def __init__(self,a,b,c):
 3         print('元类的构造函数执行')
 4         # print(a)
 5         # print(b)
 6         # print(c)
 7     def __call__(self, *args, **kwargs):
 8         # print('=-======>')
 9         # print(self)
10         # print(args,kwargs)
11         obj=object.__new__(self) #object.__new__(Foo)-->f1
12         self.__init__(obj,*args,**kwargs)  #Foo.__init__(f1,*arg,**kwargs)
13         return obj
14 class Foo(metaclass=MyType): #Foo=MyType(Foo,'Foo',(),{})---》__init__
15     def __init__(self,name):
16         self.name=name #f1.name=name
17 # print(Foo)
18 # f1=Foo('alex')
19 # print(f1)
20 
21 f1=Foo('alex')
22 print(f1)
23 print(f1.__dict__)