Asyncio

nested.py

import asyncio

async def stuff(val):
    print("Going to sleep for", val)
    await asyncio.sleep(val)
    print("slept")
    return val * 2

def do_stuff():
    print("do stuff")
    task = asyncio.ensure_future(stuff(1))
    loop = asyncio.get_event_loop()
    loop.run_until_complete(task)
    print("Task result is", task.result())

async def main():
    print("Start main")
    do_stuff()
    print("Main complete")

output

>>> do_stuff()
do stuff
Going to sleep for 1
slept
Task result is 2

>>> loop = asyncio.get_event_loop()
>>> loop.run_until_complete(main())
Traceback
...
RuntimeError: This event loop is already running

@dpnova But I think that WKWebView must be registered with the event loop on the main(UI) thread.

Also, even if this task delegated to another thread, using any synchronous way to get the result will still block the main thread and freeze the GUI.

The intention of the original issue(beeware/toga#68) is that I want to effectively avoid cases like this to freeze the GUI.