issubclass

 issubclass(cls, class_or_tuple, /)

     Return whether 'cls' is a derived from another class or is the same class.
     

 class A:

     pass

 class B(A):

     pass

 class C:

     pass

 print(issubclass(A,(B,A)))  # 一个类会被认为自己的子类 .

 print(issubclass(A,B))      # 第一个是否是第二个类的子类

 print(issubclass(B,(A,C)))

 help(issubclass)

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 True

 True

 True

 False

 >>> 

 #isinstance   检查一个实例对象是否属于一个类 . (第二个也可以是一个元祖 可以有多个类.)

 class A:

     pass

 class B(A):

     pass

 class C:

     pass

 b1=B()

 print(isinstance(b1,A))

 print(isinstance(b1,B))

 print(isinstance(b1,C))

 print(isinstance(b1,(C,B)))

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 True

 True

 False

 True

 >>> 

 #   hasattr(第一个是对象.第二个是属性名)    (attr=attribute 属性)

 class A:

     pass

 class B(A):

     pass

 class C:

     def __init__(self,x=0):

         self.x=x

 #测试一个对象是否有指定的和属性.

 c1=C()

 print(hasattr(c1,'x'))# 属性必须用 '' 来 修饰

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 True

 >>> 

 #   getattr(object,name[,default)   返回对象指定的属性值 如果指定的参数不存在 如果你制订了default则会defaulf打印出来,否则会有一个arrtibute的异常 ,

 class A:

     pass

 class B(A):

     pass

 class C:

     def __init__(self,x=0):

         self.x=x

 c1=C()

 print(getattr(c1,'x'))

 print(getattr(c1,'y','您所访问的属性不存在'))

 0

 您所访问的属性不存在

 >>> 

 class A:

     pass

 class B(A):

     pass

 class C:

     def __init__(self,x=0):

         self.x=x

 c1=C()

 print(getattr(c1,'y','您访问的属性不存在'))

 print(setattr(c1,'y',0))

 print(getattr(c1,'y','您访问的属性不存在'))

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 您访问的属性不存在

 None

 0

 >>> 

 class A:　　　　

     pass

 class B(A):

     pass

 class C:

     def __init__(self,x=0):

         self.x=x

 c1=C()

 print(getattr(c1,'y','您访问的属性不存在'))

 print(setattr(c1,'y',0))

 print(getattr(c1,'y','您访问的属性不存在'))

 print(delattr(c1,'y'))

 print(getattr(c1,'y','您访问的属性不存在'))

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 您访问的属性不存在

 None

 0

 None

 您访问的属性不存在

 >>> 

 class C:

     def __init__(self,size=10):

         self.size=size

     def getSize(self):

         return self.size

     def setSize(self,value):

         self.size=value

     def delSize(self):

         del self.size

     x=property(getSize,setSize,delSize,'这个难道是注释')

 c1=C()      # 生成一个 对象实例

 print(c1.getSize())     # 调用getSize()函数 . 

 print(c1.x)         

 c1.x=18

 print(c1.size)  # 调用 size 属性 . 

 print(c1.getSize())

 del c1.x

 print(c1.size)

 =============== RESTART: C:/Users/Administrator/Desktop/new.py ===============

 10

 10

 18

 18

 Traceback (most recent call last):

   File "C:/Users/Administrator/Desktop/new.py", line 30, in <module>

     print(c1.size)

 AttributeError: 'C' object has no attribute 'size'

 >>>