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Comment by MBlume | Hacker News Reader

Are you actually planning to lose Python 2 compatibility is porting to 3? It might make more sense to keep both if you can, if only because if you give up Python 2, there'll be an intermediate period where the code won't run anywhere.

Python six is a library that might help with targeting both

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Code that supports both py2 and py3 is often ugly and a pain to work with.

I think your advice might be well intended, but if followed will end up with an overloaded dev. and no new progress being made (and all that for the five guys who still don't have py3 installed)

Sorry to sound harsh, but I wish someone had told me that advice when I accepted to backport a py3 package to py2

Wow! The community has turned a corner! :-)

I don't believe 2-3 compatibility must be ugly (though it certainly can be), but I'm glad you believe what you said. If that makes sense.

It's not only the compatibility that is ugly. It's also that python 2 code has a couple of ugly warts, such as the forced arguments for super(). The only way I'm supporting python 2 with my libraries is by running 3to2 and pasteurize (future package) over the python 3 source code.

I really don't want to actually have source code that works on both, it's a pain to maintain. Although the future library should make it a lot nicer, but you still need a lot of ugly from __future__ imports as well.

I've been using 3.6 for some personal work and man are f-strings and ordered dicts wonderful. I don't want to go back.

1_000_000 times this.

OrderedDict is just a stdlib import away in Py2.7.

Yeah, but... those are ugly. ``m = {}`` is beautiful.

dict == OrderedDict is a cpython implementation detail. Not doing the import is just leaving a footgun for yourself if you ever decide to try PyPy or VOC or similar.

I don't think it's much of a footgun, and I don't think it's limited to CPython.

In Python 3.6, kwargs are ordered. In all versions of Python, kwargs are a dict. Therefore, in any implementation of Python 3.6, dicts are ordered.

The dev team has stopped short of promising that dicts are ordered, but I can't see how one would realistically be harmed by assuming it to be true.

The 3.6 CPython dict item storage algorithm was implemented in PyPy first.

> when I accepted to backport a py3 package to py2

I'd expect backporting from 3 to 2 to be more of a pain than porting from 2 to 3.

You might have experience with both, but if not, this seems worth bearing in mind.

If you are porting from 2.7 and don't require compatibility with earlier Python versions, then "future" [1] is a better, cleaner alternative to six.

[1] https://pypi.python.org/pypi/future

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