【脚本语言系列】关于Python基础知识兼容Python 2.x+Python 3.x，你需要知道的事

如何兼容Python 2.x+Python 3.x

• 保留字变函数
  Python 2.x使用__future__模块使用Python 3.x中的函数

# -*- coding:utf-8 -*-# For Python 2.xprint print

  File "<ipython-input-13-8fe752f7a342>", line 3    print print              ^SyntaxError: invalid syntax

# -*- coding:utf-8 -*-# For Python 2.x & Python 3.xfrom __future__ import print_functionprint(print)

<built-in function print>

• 模块更名
  使用try/except模块处理Python 2.x与Python 3.x不同名的模块

# -*- coding:utf-8 -*-# For Python 2.x & Python 3.xtry:    import urllib.request as urllib_request # For Python 3.xexcept ImportError:    import urllib2 as urllib_request # For Python 2.x

• 模块/功能过时
  使用future模块禁用Python 2.x可用但Python 3.x过时的模块

# -*- coding:utf-8 -*-# For Python 2.x & Python 3.xfrom future.builtins.disabled import *apply()

---------------------------------------------------------------------------NameError                                 Traceback (most recent call last)<ipython-input-15-99a87af09d54> in <module>()      3 from future.builtins.disabled import *      4 ----> 5 apply()c:\python27\lib\site-packages\future\builtins\disabled.pyc in disabled(*args, **kwargs)     55         no longer a builtin in Python 3.     56         '''---> 57         raise NameError('obsolete Python 2 builtin {0} is disabled'.format(name))     58     return disabled     59 NameError: obsolete Python 2 builtin apply is disabled

什么是兼容Python 2.x+Python 3.x

常用的兼容Python2.x和Python3.x的方式是：
* 开发2个模块，分别针对Python 2.x和针对_ Python 3.x_；
* 使用兼容模块，用于兼容Python 2.x和Python 3.x；