对于类似字符串的良好鸭子类型方法，它具有与Python 2同时使用的好处。X和3.x:

def is_string(obj):
    try:
        obj + ''
        return True
    except TypeError:
        return False

Wisefish在切换到isinstance方法之前与duck-typing很接近，只是+=对于列表的含义与+不同。

Python 2和3

(cross-compatible)

如果你想检查不考虑Python版本(2。x vs . 3.x)，使用six (PyPI)及其string_types属性:

import six

if isinstance(obj, six.string_types):
    print('obj is a string!')

在六个(一个非常轻量级的单文件模块)中，它只是这样做的:

import sys
PY3 = sys.version_info[0] == 3

if PY3:
    string_types = str
else:
    string_types = basestring

if type(varA) == str or type(varB) == str:
    print 'string involved'

从 EDX -在线课程 MITx: 6.00.1x使用Python的计算机科学和编程介绍

我发现这句话更夸张:

if type(aObject) is str:
    #do your stuff here
    pass

由于类型对象是单例的，is可以用来比较对象和STR类型

对于类似字符串的良好鸭子类型方法，它具有与Python 2同时使用的好处。X和3.x:

def is_string(obj):
    try:
        obj + ''
        return True
    except TypeError:
        return False

Wisefish在切换到isinstance方法之前与duck-typing很接近，只是+=对于列表的含义与+不同。

今天晚上，我遇到了一种情况，我认为我必须检查str类型，但事实证明我没有。

我的解决问题的方法可能在许多情况下都有效，所以我在下面提供它，以防其他人对这个问题感兴趣(仅限Python 3)。

# NOTE: fields is an object that COULD be any number of things, including:
# - a single string-like object
# - a string-like object that needs to be converted to a sequence of 
# string-like objects at some separator, sep
# - a sequence of string-like objects
def getfields(*fields, sep=' ', validator=lambda f: True):
    '''Take a field sequence definition and yield from a validated
     field sequence. Accepts a string, a string with separators, 
     or a sequence of strings'''
    if fields:
        try:
            # single unpack in the case of a single argument
            fieldseq, = fields
            try:
                # convert to string sequence if string
                fieldseq = fieldseq.split(sep)
            except AttributeError:
                # not a string; assume other iterable
                pass
        except ValueError:
            # not a single argument and not a string
            fieldseq = fields
        invalid_fields = [field for field in fieldseq if not validator(field)]
        if invalid_fields:
            raise ValueError('One or more field names is invalid:\n'
                             '{!r}'.format(invalid_fields))
    else:
        raise ValueError('No fields were provided')
    try:
        yield from fieldseq
    except TypeError as e:
        raise ValueError('Single field argument must be a string'
                         'or an interable') from e

一些测试:

from . import getfields

def test_getfields_novalidation():
    result = ['a', 'b']
    assert list(getfields('a b')) == result
    assert list(getfields('a,b', sep=',')) == result
    assert list(getfields('a', 'b')) == result
    assert list(getfields(['a', 'b'])) == result