I'm writing cross-compatible Python 2 and 3 code with some help from this cheatsheet. I've noticed there are different packages and modules that help to do this: the future package (e.g. future.utils etc), the six package, and the built in __future__ module.
Are there any differences to be aware of when using these packages? Should I be mixing and matching them, or is it possible to write fully cross-compatible code be written with just one of them?
In terms of python 2-3 compatibility:
__future__ - is a built-in module in python which allows you to use optional features in python versions where they are optional (vs mandatory). For example, unicode_literals was optional in python2.7 but became mandatory in python3.0.
six - mostly renames modules/functions to produce higher compatibility between python2 to python3, but doesn't actually backport (or forward-port) functionality. It is also supported for python versions >=2.4.
future - more modern, only supports python>=2.6,>=3.3, and is more rich in features.
Seems like there is some agreement that future is preferred to six if you can drop support for old versions of python.