On 11 July 2015 at 15:16, Nathaniel Smith <njs@pobox.com> wrote:
For what it's worth, I find it extraordinarily confusing that background tasks don't run in the background and foreground tasks don't run in the foreground.
I think the core problem lies in trying to reduce "the bare minimum you need to know to work effectively with native coroutines" to only two concepts, when there's actually three: * scheduling a coroutine in the event loop without waiting for it * executing a call in a background thread or process * running the event loop in the foreground while waiting for one of the above two operations I'm trying to do this *without* requiring folks to actually know what a future is: I want them to be able to use asyncio *without* learning about all the moving parts first. Once they appreciate what it can do for them, *then* they may have the motivation to tackle the task of figuring out how all the pieces fit together. However, In the design I put together for the blog posts, "run_in_background" currently handles both of the first two tasks, and it likely makes more sense to split them, which would give: def run_in_foreground(task, *, loop=None): """Runs the given event loop in the current thread until the task completes If not given, *loop* defaults to the current thread's event loop Returns the result of the task. For more complex conditions, combine with asyncio.wait() To include a timeout, combine with asyncio.wait_for() """ # Convenience wrapper around get_event_loop + # ensure_future + run_until_complete ... def schedule_coroutine(target, *, loop=None): """Schedules target coroutine in the given event loop If not given, *loop* defaults to the current thread's event loop Returns the scheduled task. Use run_in_foreground to wait for the result. """ # This just means extracting the coroutine part of # asyncio.ensure_future out to its own function. ... def call_in_background(target, *, loop=None, executor=None): """Schedules and starts target callable as a background task If not given, *loop* defaults to the current thread's event loop If not given, *executor* defaults to the loop's default executor Returns the scheduled task. Use run_in_foreground to wait for the result. """ # Convenience wrapper around get_event_loop + run_in_executor ... I'll sleep on that, and if I still like that structure in the morning, I'll look at revising my coroutine posts. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia