At 09:50 AM 1/16/2007 -0800, Guido van Rossum wrote: >Actually it's very easy to write code using keys(), items() and >values() that works as well in 2.2 as it works in 3.0: never use the >iter* variants, and don't sweat the performance costs of creating a >list so much. If you can't afford to create a list, iterate over the >dict itself, which will give you the keys in both versions.
Actually, the main reason I use items() or keys() is because I want to mutate the dictionary, or because something else is going to mutate it while I'm looping over it. But yeah, that discussion should be on Py3K. >>Without having at least *some* 2.x version that can run 3.x code, I think >>there is little chance of 3.0 becoming viable. You've been comparing this >>to Zope 2/Zope 3, but in that world there is something called "Five" that >>lets you do Zope 3 things inside of Zope 2, so you have some chance of >>porting your code in an incremental fashion, without having to leap >>everything over in one go. > >I'm not aware of compromises to 3.0's architecture that were made in >order to ease the transition though -- all of the burden was placed on >Zope 2.x (though perhaps some optional compatibility packages were >also added to Zope 3.0?). Right, which is why I don't think we should worry about 2.5 as much as 2.6. >>The analogy isn't perfect, because we are not so much trying to provide >>backward compatibility in "Excel" as to add *forward* compatibility to >>"123", but you get the idea. > >Such analogies are hard to get right; in this case he's talking about >file interchange formats. Perhaps the closest analogy is pickling. Actually, I meant the analogy for *code*. If you can't write code that runs on some 2.x + 3.x combination, you have no way to cross the chasm. If you're writing "spreadsheets for Excel" (code that runs on 3.x), you need to be able to "share them with 1-2-3 users" (run that code on 2.x). _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
