On Thu, Nov 20, 2014 at 11:36:54AM -0800, Guido van Rossum wrote: [...] > That said, I think for most people the change won't matter, some people > will have to apply one of a few simple fixes, and a rare few will have to > rewrite their code in a non-trivial way (sometimes this will affect > "clever" libraries). > > I wonder if the PEP needs a better transition plan, e.g. > > - right now, start an education campaign > - with Python 3.5, introduce "from __future__ import generator_return", and > silent deprecation warnings > - with Python 3.6, start issuing non-silent deprecation warnings > - with Python 3.7, make the new behavior the default (subject to some kind > of review)
I fear that there is one specific corner case that will be impossible to deal with in a backwards-compatible way supporting both Python 2 and 3 in one code base: the use of `return value` in a generator. In Python 2.x through 3.1, `return value` is a syntax error inside generators. Currently, the only way to handle this case in 2+3 code is by using `raise StopIteration(value)` but if that changes in 3.6 or 3.7 then there will be no (obvious?) way to deal with this case. -- Steven _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
