[Python-Dev] Proposed 3.0 compatiblity module (original) (raw)

Steve Holden steve at holdenweb.com
Tue Jan 16 23:23:04 CET 2007

Phillip J. Eby wrote:

At 08:52 PM 1/16/2007 +0000, Steve Holden wrote:

I foresee that many people would be happy restricting their 2.X source slightly to ensure perfect translation into (working, no necessarily optimal) 3.0. Under those circumstances the 2to3 tool wouldn't necessarily have to translate all valid 2.X to 3.0. Actually, it would be several times more preferable to either have that restricted subset of code run on 3.0 without translation, or for translated code to still be usable in 2.X. I have often been in the habit of running test suites back-to-back on multiple versions of Python while doing test-driven development, so having a repeated translation step would interfere with that. Ideally, a translation should be necessary one time only -- in which case requiring manual cleanup steps isn't as big of a problem. The idea here being that, once 2.6 is widely-enough deployed that it can be assumed as a base for one's users, you can simply run the translator once, do any cleanup, and then have 3.0-clean code that also still runs for your installed base. That way, there's no chasm to leap; just a code cleanup. That assumes that once you convert to 3.0 you are no longer interested in back-porting further functionality changes to your 2.X code, surely, or am I missing something?

It seems to me preferable to allow repeated translation of 2.X code to working no-fixes-required 3.0. Then the cleanup step is required only when withdrawing support (or development) for 2.X and making the final translation. At that point it would be a one-time task.

Or are you suggesting that users make the change to 3.0 and then backport changes to 2.X where necessary using the older semantics? In either case you end up with two different code bases.

regards Steve

Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden Blog of Note: http://holdenweb.blogspot.com

More information about the Python-Dev mailing list