[New-bugs-announce] [issue26969] ascynio should provide a policy to address pass-loop-everywhere problem

[Ilya Kulakov]

New submission from Ilya Kulakov:

Currently if one needs lazily resolve event loop depending on where awaitable is being awaited have to pass loop everywhere explicitly. That quickly becomes an unnecessary noise in interfaces of callables. 

Consider an example where a coroutine which constructs other awaitables can be executed in arbitrary loop:

    import asyncio
    import datetime

    async def foo_coro(loop):
        await some_other_coro(loop)

    async def bar_coro(loop):
        await asyncio.ensure_future(..., loop=loop)

    async def baz_coro(loop):
        await asyncio.gather(foo_coro(loop), bar_coro(loop), loop=loop)

    loop = asyncio.get_event_loop()
    loop.run_until_complete(multiple_coros(loop))
    loop.close()

It would be nice, if all functions that belong to an event loop instance as well as asyncio helpers that accept a loop would set default event loop to one that was passed to these functions. So that the example above could be rewritten as:

    import asyncio
    import datetime

    async def foo_coro():
        await some_other_coro()

    async def bar_coro():
        await asyncio.ensure_future(...)

    async def baz_coro():
        await asyncio.gather(foo_coro(), bar_coro())

    loop = asyncio.get_event_loop()
    loop.run_until_complete(multiple_coros())
    loop.close()

----------
components: asyncio
messages: 264941
nosy: Ilya.Kulakov, gvanrossum, haypo, yselivanov
priority: normal
severity: normal
status: open
title: ascynio should provide a policy to address pass-loop-everywhere problem
type: enhancement
versions: Python 3.4, Python 3.5, Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue26969>
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