On Wed, Aug 13, 2014 at 05:51:40PM -0430, Juancarlo AƱez wrote:
Function annotations are not available in Python 2.7, so promoting widespread use of annotations in 3.5 would be promoting code that is compatible only with 3.x,
Yes. You say that as if it were a bad thing. It is not. Python 3 is here to stay and we should be promoting Python 3 only code. There is absolutely no need to apologise for that fact. If people are happy with Python the way it is in 2.7, or 1.5 for that matter, that's great, they can stay on it for ever, but all new features are aimed at 3.x and not 2.x or 1.x.
when the current situation is that much effort is being spent on writing code that works on both 2.7 and 3.4 (most libraries?).
There's no reason why all new code should be aimed at 2.x and 3.x. But even for code which is, the nice thing about this proposal is that it's optional, so you can run your type-check using mypy under Python 3.x and still get the benefit of it when running under 2.x.
Independently of its core merits, this proposal should fail unless annotations are added to Python 2.8.
There will be no Python 2.8, and no Python 2.9 either. New features go into 3.x. -- Steven