How to make scripts compatible with both Python 2 and python 3?

Want to make APP Same thing as WeChat , Can run small programs smoothly ？ | Experience will send you to Xinjiang 、 Huawei 、 Cherry keyboard ！>>>

　　 The problem developers often encounter is , Yes ⼀ individual ⾮ Often famous Python Modules are used by many developers ⽤ the , But not all ⼈ They only make ⽤Python2 perhaps Python3. At this point, you have two ways . The first ⼀ One way is to develop two modules , in the light of Python2⼀ individual , in the light of Python3⼀ individual . also ⼀ One way is to adjust your current code to be compatible at the same time Python2 and Python3. This article will introduce ⼀ Some ways , Make your scripts compatible at the same time Python2 and Python3.

　　Future Module leads to ⼊

　　 That's the most important thing ⽅ Law , That is to guide ⼊__future__ modular . It can help you in Python2 Midcourse ⼊Python3 The function of . There are ⼀ Group example ⼦. Up and down ⽂ The manager is Python2.6+ lead ⼊ New features , If you want to Python2.5 Chinese envoy ⽤ It can do this ：

　　from __future__ import with_statement

　　 stay Python3 in print Has changed to ⼀ A function . If you want to Python2 Chinese envoy ⽤ It can go through __future__ guide ⼊：

　　print

　　# Output:

　　from __future__ import print_function

　　print(print)

　　# Output:

　　 Module renaming

　　⾸ First ,⼤ Most of the time, we'll do this in scripts ⼊ modular ：

　　import foo

　　# or

　　from foo import bar

　　 You can do the same ：

　　import foo as foo

　　 This can work and ⾯ Code has the same function , But the most important thing is that it makes your scripts compatible at the same time Python2 and Python3. Now let's take a look ⾯ Code for ：

　　try:

　　import urllib.request as urllib_request # for Python 3

　　except ImportError:

　　import urllib2 as urllib_request # for Python 2

　　 A little explanation ⼀ Down and up ⾯ Code for . We will lead the module to ⼊ The code is packaged in try/except In the sentence . We do this because of Python 2 Not in China urllib.request modular . This will cause ⼀ individual ImportError abnormal .⽽ stay Python2 in urllib.request The function of urllib2 Provided . therefore , When we try to be in Python2 Midcourse ⼊urllib.request Module time ,⼀ Once we catch ImportError We will guide ⼊urllib2 Module to replace it .

　　 Last , You need to understand as Key words ⽤. It will lead to ⼊ Module mapping to urllib.request, So we went through urllib_request This alias can make ⽤urllib2 All classes in and ⽅ Yes .

　　 overdue Python2 The built-in function

　　 another ⼀ One thing to know is Python2 There is 12 Built in features in Python3 Has been removed . Make sure that Python2 Don't use these functions in the code to ensure that it is correct for Python3 Compatibility . There are ⼀ A compulsion to give up 12 Built in features ⽅ Law ：

　　from future.builtins.disabled import *

　　 Now? , As long as you try to be in Python3 Chinese envoy ⽤ These abandoned modules are , Will throw ⼀ individual NameError abnormal , as follows ：

　　from future.builtins.disabled import *

　　apply()

　　# Output: NameError: obsolete Python 2 builtin apply is disabled

　　 Standard library down compatible with external ⽀ a

　　 Yes ⼀ Some bags are in ⾮ Officer, ⽅ Of ⽀ Hold on to Python2 Provides Python3 The function of . For example, we have ：

　　enum pip install enum34

　　singledispatch pip install singledispatch

　　pathlib pip install pathlib

　　 That's all the way , See here , I believe you have already understood how to make scripts compatible at the same time Python2 and Python3. If you want to learn more about Python Dry goods of , You can find a lot of high quality Python Online courses , Let's see ~ Zhengzhou infertility hospital which good :http://yyk.39.net/zz3/zonghe/fc964.html Which is the best hospital in Zhengzhou :http://yyk.39.net/zz3/zonghe/1d426.html Zhengzhou gynecological hospital :http://jbk.39.net/yiyuanfengcai/yyjs_sysdfkyy/