Using an Event is slightly better because you just wait for it -- you don't have to catch an exception. It's just not one of the better-known parts of asyncio.
On Fri, Dec 18, 2015 at 1:42 PM, Andrew Barnert <abarn...@yahoo.com> wrote: > On Friday, December 18, 2015 1:09 PM, Guido van Rossum <gu...@python.org> > wrote: > > > >I guess we could make the default arg to sleep() 1e9. Or make it None and > special-case it. I don't feel strongly about this -- I'm not sure how > baffling it would be to accidentally leave out the delay and find your code > sleeps forever rather than raising an error (since if you don't expect the > infinite default you may not expect this kind of behavior). > > Yeah, that is a potential problem. > > The traditional C solution is to just allow passing -1 to mean "forever",* > ideally with a constant so you can just say "sleep(FOREVER)". Which, in > Python terms, would presumably mean "asyncio.sleep(asyncio.forever)", and > it could be a unique object or an enum value or something instead of > actually being -1. > > * Or at least "until this rolls over 31/32/63/64 bits", which is where you > get those 49-day bugs from... but that wouldn't be an issue in Python > > > But I do feel it's not important enough to add a new function or method. > > Definitely agreed. > >However, I don't think "forever" and "until cancelled" are really the > same thing. "Forever" can only be interrupted by loop.stop(); "until > cancelled" requires indicating how to cancel it, and there the OP's > approach is about the best you can do. (Or you could use the Event class, > but that's really just a wrapper on top of a Future made to look more like > threading.Event in its API.) > > > OK, I thought the OP's code looked pretty clear as written: he wants to > wait until cancelled, so he waits on something that pretty clearly won't > ever finish until he's cancelled. If that (or an Event or whatever) is the > best way to spell this, then I can't really think of any good uses for > sleep(forever). > -- --Guido van Rossum (python.org/~guido)
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