python 面向对象拓展isinstance 和issubcalss函数

isinstance判断对象是否为类的实例。

n1 = 9
print isinstance(n1,str)

True

class A:
    pass
class B(A):
    pass
a =B()
print isinstance(a,A)

True

 issubcalss判断类是否为子类

class A:
    pass
class B(A):
    pass
print issubclass(B,A)

True