On 24 July 2014 05:54, Terry Reedy <tjre...@udel.edu> wrote: > On 7/23/2014 6:43 AM, Saimadhav Heblikar wrote: >> >> Hi, >> >> The example in question is >> >> https://docs.python.org/3/library/asyncio-task.html#example-hello-world-coroutine. >> I'd like to learn the purpose of the statement >> "yield from asyncio.sleep(2)" in that example. >> >> In particular, I'd like to know if asyncio.sleep() is used as a >> substitute for slow/time consuming operation, i.e. in real code, >> whether there will be a real time consuming statement in place of >> asyncio.sleep(). > > > The context is > while True: > print('Hello') > yield from asyncio.sleep(3) > > sleep is both itself, to shown to schedule something at intervals in a > non-blocking fashion, as well as a placefiller. The blocking equivalent > would use 'time' instead of 'yield from asyncio'. The following shows the > non-blocking feature a bit better. > > import asyncio > > @asyncio.coroutine > def hello(): > while True: > print('Hello') > yield from asyncio.sleep(3) > > @asyncio.coroutine > def goodbye(): > while True: > print('Goodbye') > yield from asyncio.sleep(5.01) > > @asyncio.coroutine > def world(): > while True: > print('World') > yield from asyncio.sleep(2.02) > > loop = asyncio.get_event_loop() > loop.run_until_complete(asyncio.wait([hello(), goodbye(), world()])) > > Getting the same time behavior in a while...sleep loop requires reproducing > some of the calculation and queue manipulation included in the event loop. > > -- > Terry Jan Reedy > > -- > https://mail.python.org/mailman/listinfo/python-list
That clears it up for me. For situations where I dont really know how long a function is going to take(say waiting for user input or a network operation), I am better off using callbacks than "yield from asyncio.sleep()". Is my understanding correct? -- Regards Saimadhav Heblikar -- https://mail.python.org/mailman/listinfo/python-list
