python isinstance

isinstance(object，type)常用来判断一个对象是否是一个已知的类型。 
其第参数object为对象，第二个参数type为类型名如int、str，或类型名的一个列表如[int,str,tuple,list,float]。
其返回值为布尔型（True 或 Flase）。若对象的类型与参数二的类型相同则返回True。若参数type为一个元组，参数object类型与元组中类型名之一相同也返回True。

>>> help(isinstance)Help on built-in function isinstance in module __builtin__:isinstance(...)    isinstance(object, class-or-type-or-tuple) -> bool        Return whether an object is an instance of a class or of a subclass thereof.    With a type as second argument, return whether that is the object's type.    The form using a tuple, isinstance(x, (A, B, ...)), is a shortcut for    isinstance(x, A) or isinstance(x, B) or ... (etc.).>>>

1、参数object为常用类型：

>>> a = 2>>> isinstance(a,int)True>>> isinstance(a,float)False>>> type(a)<type 'int'>>>> s = 'abc'>>> type(s)<type 'str'>>>> isinstance(s,str)True>>> isinstance(2.5,float)True

2、参数object为列表、元祖、字典：

>>> lst = [1,2,'3',4]>>> type(lst)<type 'list'>>>> isinstance(lst,list)True>>> tpl = (5,6,7)>>> type(tpl)<type 'tuple'>>>> isinstance(tpl,tuple)True>>> dic = {a:8,b:9,c:10}Traceback (most recent call last):  File "<pyshell#14>", line 1, in <module>    dic = {a:8,b:9,c:10}NameError: name 'a' is not defined>>> dic = {'a':8,'b':9,'c':10}>>> isinstance(dic,dict)True>>> 

3、参数object为类：（建议使用isinstance判断对象，少用type。）

>>> class BaseClass:pass>>> class SubClass:pass>>> isinstance(BaseClass(),BaseClass)True>>> type(BaseClass())<type 'instance'>>>> type(BaseClass()) == BaseClassFalse>>> c = SubClass()>>> isinstance(c,SubClass)True>>> 

4、参数type为元祖：

>>> >>> isinstance(c,(int,str,list))False>>> isinstance(c,(int,str,list,SubClass))True>>> t = (int,str,list,SubClass)>>> isinstance(c,t)True>>>