Should I keep my Python code at 2.x or migrate to 3.x if I plan to eventually use Jython?

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+3 Q:

Should I keep my Python code at 2.x or migrate to 3.x if I plan to eventually use Jython?

I have a large infrastructure that is written in Python 2.6, and I recently took a stab at porting to 3.1 (was much smoother than I expected) despite the lack of backwards compatibility.

I eventually want to integrate some of this Python code with a lot of Java based code that we have, and was thinking about giving Jython a try. However, from looking at the Jython tutorials, all the examples are in 2.6 syntax (e.g., print is not yet a function).

Does/will Jython support Python 3.x syntax at present or in the near future? Or should I roll back to 2.6 if I want to eventually use Jython?

+5 A:

Jython will not support Python 3.x in the near future. For your code, I recommend to keep it in 2.x form, such that 3.x support becomes available by merely running 2to3 (i.e. with no further source changes). IOW, port to 3.x in a way so that the code remains compatible with 2.x.

Martin v. Löwis 2009-10-14 14:05:38

Thank you. Most of my difficulties were with the print statement (of all things), so maybe I will create some bridge method that I can change in the future as I migrate between versions. Is Python 3 that different that Jython compatibility would be difficult?

Uri 2009-10-14 14:10:35

In Python 2.6 you can do from __future__ import print_function. However I don't know when/if Jython plans to support that.

Lennart Regebro 2009-10-14 14:16:22

@Uri: don't worry about the print function. This is *exactly* what 2to3 was designed to support, so if you have manually adjusted it, you have wasted your time :-( As for Jython: yes, implementing Python 3 will be quite some effort. I'm sure it will happen eventually, but you were asking for the near future (e.g. whether anything is in the works).

Martin v. Löwis 2009-10-14 14:19:13

@Martin: I appreciate it. I used the print transition to do some cleanups and add internal logging levels so it wasn't a waste. But there are minor things that I had to change.

Uri 2009-10-14 14:25:12

Using 3to2 (http://bitbucket.org/amentajo/lib3to2) is also a good option for supporting both versions.

Ants Aasma 2009-10-14 14:55:49

I would expect that the developers will be working towards compatability with 3.0 at this point. Since they released 2.5 in june I'd hope for a 3.0 version no earlier than Jan.-Mar. 2010, but given their slow release cycle, it could be a while.

chills42 2009-10-14 14:09:12

With time 2.x will be surpassed by the new features of his 3.x. If you wish to programming in Python in the future then "the sooner = the better"

Catalin Festila 2009-10-14 17:19:12

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Should I keep my Python code at 2.x or migrate to 3.x if I plan to eventually use Jython?

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