使用str代替string

type ( obj ) == str

解释

>>> a = "Hello"
>>> type(a)==str
True
>>> type(a)
<type 'str'>
>>>

对于其他类型，请查看types模块:

>>> import types
>>> x = "mystring"
>>> isinstance(x, types.StringType)
True
>>> x = 5
>>> isinstance(x, types.IntType)
True
>>> x = None
>>> isinstance(x, types.NoneType)
True

注:类型检查是个坏主意。

使用isinstance(object, type)。如上所述，如果你知道正确的类型，这很容易使用，例如，

isinstance('dog', str) ## gives bool True

但对于更深奥的对象，这可能很难使用。 例如:

import numpy as np 
a = np.array([1,2,3]) 
isinstance(a,np.array) ## breaks

但你可以用这个技巧:

y = type(np.array([1]))
isinstance(a,y) ## gives bool True 

所以我建议用你想检查的对象类型(例如，type(np.array())实例化一个变量(在本例中是y)，然后使用isinstance。

您可以比较类的检查级别。

#!/usr/bin/env python
#coding:utf8

class A(object):
    def t(self):
        print 'A'
    def r(self):
        print 'rA',
        self.t()

class B(A):
    def t(self):
        print 'B'

class C(A):
    def t(self):
        print 'C'

class D(B, C):
    def t(self):
        print 'D',
        super(D, self).t()

class E(C, B):
    pass

d = D()
d.t()
d.r()

e = E()
e.t()
e.r()

print isinstance(e, D) # False
print isinstance(e, E) # True
print isinstance(e, C) # True
print isinstance(e, B) # True
print isinstance(e, (A,)) # True
print e.__class__ >= A, #False
print e.__class__ <= C, #False
print e.__class__ <  E, #False
print e.__class__ <= E  #True

要获取类型，使用__class__成员，如unknown_thing.__class__

Talk of duck-typing is useless here because it doesn't answer a perfectly good question. In my application code I never need to know the type of something, but it's still useful to have a way to learn an object's type. Sometimes I need to get the actual class to validate a unit test. Duck typing gets in the way there because all possible objects have the same API, but only one is correct. Also, sometimes I'm maintaining somebody else's code, and I have no idea what kind of object I've been passed. This is my biggest problem with dynamically typed languages like Python. Version 1 is very easy and quick to develop. Version 2 is a pain in the buns, especially if you didn't write version 1. So sometimes, when I'm working with a function I didn't write, I need to know the type of a parameter, just so I know what methods I can call on it.

这就是__class__参数派上用场的地方。这(据我所知)是获取对象类型的最佳方法(可能是唯一的方法)。

我想这个就可以了

if isinstance(obj, str)