On Tue, 24 May 2016 at 12:20 guido.van.rossum <python-check...@python.org> wrote:
> https://hg.python.org/peps/rev/50c3f5aefbb7 > changeset: 6341:50c3f5aefbb7 > user: Guido van Rossum <gu...@python.org> > date: Tue May 24 12:18:54 2016 -0700 > summary: > Short subsection on annotating coroutines (Ivan L, #225). > > files: > pep-0484.txt | 34 ++++++++++++++++++++++++++++++++++ > 1 files changed, 34 insertions(+), 0 deletions(-) > > > diff --git a/pep-0484.txt b/pep-0484.txt > --- a/pep-0484.txt > +++ b/pep-0484.txt > @@ -1015,6 +1015,40 @@ > ellipsis, i.e. the above example is literally what you would write. > > > +Annotating generator functions and coroutines > +--------------------------------------------- > + > +The return type of generator functions can be annotated by > +the generic type ``Generator[yield_type, send_type, > +return_type]`` provided by ``typing.py`` module:: > + > + def echo_round() -> Generator[int, float, str]: > + res = yield > + while res: > + res = yield round(res) > + return 'OK' > + > +Coroutines introduced in PEP 492 are annotated with the same syntax as > +ordinary functions. However, the return type annotation corresponds to the > +type of ``await`` expression, not to the coroutine type:: > + > + async def spam(ignored: int) -> str: > + return 'spam' > + > + async def foo(): > + bar = await spam(42) # type: str > If the coroutine has multiple await expressions that return different types then do you simply use a Union to express that? -Brett > + > +The ``typing.py`` module also provides generic ABCs ``Awaitable``, > +``AsyncIterable``, and ``AsyncIterator`` for situations where more precise > +types cannot be specified:: > + > + def op() -> typing.Awaitable[str]: > + if cond: > + return spam(42) > + else: > + return asyncio.Future(...) > + > + > Compatibility with other uses of function annotations > ===================================================== > > > -- > Repository URL: https://hg.python.org/peps > _______________________________________________ > Python-checkins mailing list > python-check...@python.org > https://mail.python.org/mailman/listinfo/python-checkins >
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