Thanks for the quick answer! I'll have a look at this PEP. Cheers
On 24/03/2017 16:17, Jelle Zijlstra wrote: > > > 2017年03月24日 3:57 GMT-07:00 Aymeric Fromherz <[email protected] > <mailto:[email protected]>>: > > Hi, > > I'm currently looking into how Python3 is parsed, and I'm wondering why > await and async aren't considered as keywords? Are there programs > actually using await and async as variable names? Is there another > behaviour where it is interesting to use async for something different? > > They are not keywords to prevent breaking backwards compatibility, but > they will be full keywords in 3.7. async/await was introduced in 3.5, > and Python generally avoids introducing backwards-incompatible in minor > versions. Usually, that's done with __future__ imports; if I recall > correctly, when "with" statements were introduced (making "with" a > keyword), Python first released one or two versions where you had to do > "from __future__ import with_statement" to use them, and then this flag > was turned on by default. For async/await, instead the parser was hacked > to recognize "async def" as a special token, and to add special parsing > rules within "async def" function to recognize other uses of async and > await. However, this is temporary and async and await will be full > keywords in Python 3.7. > See https://www.python.org/dev/peps/pep-0492/#transition-plan. > > And yes, real code uses async and await as identifiers. asyncio itself > had a function called asyncio.async() (now renamed to ensure_future()). > Making async and await full keywords would have immediately broken any > such code for people who were upgrading to Python 3.5. > > > > Cheers, > Aymeric > _______________________________________________ > Python-Dev mailing list > [email protected] <mailto:[email protected]> > https://mail.python.org/mailman/listinfo/python-dev > <https://mail.python.org/mailman/listinfo/python-dev> > Unsubscribe: > > https://mail.python.org/mailman/options/python-dev/jelle.zijlstra%40gmail.com > > <https://mail.python.org/mailman/options/python-dev/jelle.zijlstra%40gmail.com> > > _______________________________________________ Python-Dev mailing list [email protected] https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com