On Thu, May 7, 2015 at 5:13 PM, Alexander Shorin <[email protected]> wrote:
> Assume I want to make a delayed call: > > handler = loop.call_later(delay, callback) > > How can I check if callback was called for _now_? > You can't. > Handler seems only provides a way to cancel a call, not to check it > status: is called, failed with exception etc. > Correct. > If the callback failed, how can I get an exception of it? > It will be logged, but you can't catch and examine it. > loop.set_exception_handler seems is designed to catch everything, but I > need to catch exact that callback failure. > Correct, that's not meant for this use case. > Bonus: what's the best way to delay call (delay yield from) coroutines? I > guess is something like that: > > @asyncio.coroutine > def yield_later(delay, coro): > yield from asyncio.sleep(delay) > yield from coro > > asyncio.async(yield_later(delay, mycoro(foo, bar=baz))) > > but just want to make sure. > But what are you doing with the return from the async() call? > For now, the only solution I see is about wrap callback with additional > functions in order to catch and process raised exceptions, set an Event in > order to notify callee about callback call and so on, but doing all this I > have a strange feel that I miss something oblivious. So do I? > That's indeed how you do this. Remark: you are mixing questions about callbacks and coroutines. Maybe you are not entirely sure about the difference between the two? They are meant to be used at quite different levels (in fact, coroutines make progress mostly when the event loop calls some callback that causes a Task or Future to become done). -- --Guido van Rossum (python.org/~guido)
