On Sun, Feb 7, 2021 at 6:25 PM Paul Sokolovsky <pmis...@gmail.com> wrote:
>
> Hello,
>
> On Sat, 6 Feb 2021 23:05:19 -0800
> Guido van Rossum <gu...@python.org> wrote:
>
> > That’s incorrect. __future__ is used when something new and
> > *incompatible* is being introduced (and the old way is being
> > deprecated at the same time). For experimental modules we use the
> > term provisional. There’s no official term for experimental syntax
> > (since we’ve never had any), but we could call that provisional as
> > well.
>
> Thanks, I'm aware. Thus the nature of my proposal is: redefine (extend)
> cases when __future__ is used, e.g. when a PEP itself says something
> like "There're many more could be done, but good things come in
> pieces, and wise men know when to stand back and relax before
> continuing. So, see ya next time!"
>
> My argument that such usage of __future__ would correspond more to the
> expectations of the Python end users ("feature is not fully developed
> yet, and there could be small incompatible changes going forward").But future directives are not for things that aren't fully developed yet. What gives people this idea? For example, Python 2 code can say "from __future__ import print_function" or "division". Was the print function in a provisional state, with incompatible changes coming? No. Was the division operator redefined? No. The directives cause compilation changes (removing a keyword, using a different division operator) that were backward incompatible *at launch* but they haven't changed since. In fact, part of the promise of __future__ is that it WILL remain compatible - you can write "from __future__ import nested_scopes" in a modern Python script, and the behaviour will be exactly correct. If you want a directive to put at the top of a script that says that new features are being used, I'd suggest something like this: #!/usr/bin/env python3.9 or whatever version you require. ChrisA _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/KJ2X6P2BZOW6W4Y7S6SOULWCKYQUAIGL/ Code of Conduct: http://python.org/psf/codeofconduct/
