On Fri, Sep 9, 2016 at 11:39 AM, Barry Warsaw <ba...@python.org> wrote: > On Sep 09, 2016, at 01:08 PM, Elvis Pranskevichus wrote: > >>Are there any downsides to explicitly specifying that all dicts are ordered? >>People will inevitably start relying on this behaviour, and this will >>essentially become the *de-facto* spec, so alternative Python implementations >>will have to follow suit anyway. > > It *might* make sense to revisit this once 3.5 is no longer maintained at all, > but I think Guido's exactly right in his analysis. If people start relying on > all dicts being ordered now, their code won't be compatible with both 3.5 and > 3.6, and I think it's important to emphasize this to developers.
I feel like I'm missing something here... by this reasoning, we should *never* change the language spec when new features are added. E.g. if people use async/await in 3.5 then their code won't be compatible with 3.4, but async/await are still part of the language spec. And in any case, the distinction between "CPython feature" and "Python language-spec-guaranteed feature" is *extremely* arcane and inside-basebally -- it seems really unlikely that most users will even understand what this distinction means, never mind let it stop them from writing CPython-and-PyPy-specific code. Emphasizing that this is a new feature that only exists in 3.6+ of course makes sense, I just don't understand why that affects the language spec bit. (OTOH it doesn't matter that much anyway... the language spec is definitely a useful thing, but it's largely aspirational in practice -- other implementations target CPython compatibility more than they target language spec compatibility.) -n -- Nathaniel J. Smith -- https://vorpus.org _______________________________________________ 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
