asyncio as_yielded from async generators

Question

I\'m looking to be able to yield from a number of async coroutines. Asyncio\'s as_completed is kind of close to what I\'m looking for (i.e. I want any of the corout

Answer 1

You can use aiostream.stream.merge:

from aiostream import stream

async def main():
    runs = [test_gen(i) for i in range(3)]
    async for x in stream.merge(*runs):
        print(f'{x} yielded')

Run it in a safe context to make sure the generators are cleaned up properly after the iteration:

async def main():
    runs = [test_gen(i) for i in range(3)]
    merged = stream.merge(*runs)
    async with merged.stream() as streamer:
        async for x in streamer:
            print(f'{x} yielded')

Or make it more compact using pipes:

from aiostream import stream, pipe

async def main():
    runs = [test_gen(i) for i in range(3)]
    await (stream.merge(*runs) | pipe.print('{} yielded'))

More examples in the documentation.

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Adressing @nirvana-msu comment

It is possible to identify the generator that yielded a given value by preparing sources accordingly:

async def main():
    runs = [test_gen(i) for i in range(3)]
    sources = [stream.map(xs, lambda x: (i, x)) for i, xs in enumerate(runs)]
    async for i, x in stream.merge(*sources):
        print(f'ID {i}: {x}')