[Python-Dev] Proposed 3.0 compatiblity module

[Phillip J. Eby]

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.