[Python-Dev] Smoothing the transition from Python 2 to 3 (original) (raw)

Neil Schemenauer neil at python.ca
Fri Jun 10 14:00:45 EDT 2016

On 6/10/2016 10:49 AM, Nick Coghlan wrote:

What Brett said is mostly accurate for me, except with one slight caveat: I've been explicitly trying to nudge you towards making the existing tools better, rather than introducing new tools. With modernize and futurize we have a fairly clear trade-off ("Do you want your code to look more like Python 2 or more like Python 3?"), and things like "pylint --py3k" and the static analyzers are purely additive to the migration process (so folks can take them or leave them), but alternate interpreter builds and new converters have really high barriers to adoption.

I agree with that idea. If there is anything that is "clean" enough, it should be merged with either 2.7.x or 3.x. There is nothing in my tree that can be usefully merged though.

More -3 warnings in Python 2.7 are definitely welcome (since those can pick up runtime behaviors that the static analysers miss), and if there are things the existing code converters and static analysers could detect but don't, that's a fruitful avenue for improvement as well. We are really limited on what can be done with the bytes/string issue because in Python 2 there is no distinct type for bytes. Also, the standard library does all sorts of unclean mixing of str and unicode so a warning would spew a lot of noise.

Likewise, a warning about comparison behavior (None, default ordering of types) would also not be useful because there is so much standard library code that would spew warnings.

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