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

Steve Holden steve at holdenweb.com
Tue Jan 16 21:52:32 CET 2007

Guido van Rossum wrote:

On 1/12/07, Raymond Hettinger <raymond.hettinger at verizon.net> wrote: [...]

Outside of a compatibility module, we can decide to leave Py2.6 unmolested by Py3.0, so I can stop being cranky. If you're feeling cranky this early in the new year, maybe you should look for reasons outside this list. :-) What, we're supposed to reset our crankometers on January 1? Nobody told me that.

I'm all for striving for minimal impact. I don't think we can attain zero impact.

BTW, a possible alternative would be to strive for code that runs under 2.x, and after automatic transformation using the 2to3 tool runs under 3.x, without mannual patch-up. That's probably a much lower bar, and it would still mean that developers wishing to maintain code that works with both 2.x/3.x only need to maintain a single version -- the other version could be automatically generated. Since you need to do a lot of testing anyways to make sure you haven't accidentally broken compatibility, the effort would be roughly equivalent to the "identical source" approach that people are advocating so far, and it would probably lift some restrictions. For example, working around print becoming a function would mean no use of print at all when using "identical source"; but that's a transformation that the 2to3 tool can do trivially and perfectly, so the "automatic conversion" approach would enable freely using print statements. A mixture of the two approaches would perhaps work best. 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.

cranki-ly y'rs - 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

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