Send data to asyncio coroutine

Ian Kelly ian.g.kelly at
Wed Jul 29 01:20:27 CEST 2015

On Tue, Jul 28, 2015 at 2:41 PM, Javier <jcarmena at> wrote:
> I think that force the developer to 'yield from' all function calls to keep async capabilities is a big mistake, it should be more flexible, like this:
> import asyncio
> @asyncio.coroutine
> fun non_blocking_io():
>     """ Everybody knows I'm doing non blocking IO """
>     ...
> fun foo():
>     """ I invoke functions that do IO stuff """
>     data = yield from non_blocking_io()
>     yield from store_data_db(data)
>     ...
> fun bar():
>     """ I don't know what foo implementation does """
>     foo()
> asyncio.async(bar())

Do you have a proposal for implementing this? What does "yield from"
actually do here? How does the event loop know that foo is waiting for
something and what it is waiting for?

> Does python 3.5 await/async solve this?

Yes and no. await is basically equivalent to yield from with extra
validation, so you still can't use them like what you have above. But
native coroutines are also clearly not generators as they lack
__next__ and __iter__ methods, so maybe there will be less temptation
to try to use them without using await / yield from.

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