New submission from Daniel Arbuckle: It's occasionally necessary to invoke the asyncio event loop from code that was itself invoked within (although usually not directly by) the event loop.
For example, imagine you are writing a class that serves as a local proxy for a remote data structure. You can not make the __contains__ method of that class into a coroutine, because Python automatically converts the return value into a boolean. However, __contains__ must invoke coroutines in order to communicate over the network, and it must be invokable from within a coroutine to be at all useful. If the event loop _run_once method were reentrant, addressing this problem would be simple. That primitive could be used to create a loop_until_complete function, which could be applied to the io tasks that __contains__ needs to invoke So, making _run_once reentrant is one way of addressing this request. Alternately, I've attached a decorator that sets aside some of the state of _run_once, runs a couroutine to completion in a nested event loop, restores the saved state, and returns the coroutine's result. This is merely a proof of concept, but it does work, at least in my experiments. ---------- components: asyncio files: nested.py messages: 225578 nosy: djarb, gvanrossum, haypo, yselivanov priority: normal severity: normal status: open title: asyncio: nested event loop type: enhancement Added file: http://bugs.python.org/file36422/nested.py _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue22239> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
