Thanks a lot for your helpful posts, Terry!
On 11/23/2013 01:00 AM, Terry Reedy wrote:
* Make the task function a parameter 'func'.
I actually like subclassing, but yes I know there are some downsides :)
* Rename start to _set to better describe what is does and call it in
the _run function to not repeat the handler setting line. (If 'start'
has any magic meaning, I am not aware of it. I am aware that there
could be situations in which one would want a public method, to be
called from other handlers. But that would be a different class ;-)
* Comment out the stop method because it is useless in the current
usage. I believe handler.cancel is only relevant after the handler is
set and before it is fired. This can only be done from another handler.
You are right, the handler setting line should not be repeated.
I choose start() and stop() for controlling the task because this is an
interface I would instantly understand as a user of this class.
By the way: My whole motivation is, that I want to implement such a task
class in a network library I am currently writing.
On 11/23/2013 02:33 AM, Terry Reedy wrote:
I was initially baffled also until I managed to assemble all the
needed pieces.
import asyncio
def f():
print('Hello World')
@asyncio.coroutine
def g(func, interval):
while True:
yield from asyncio.sleep(interval)
func()
loop = asyncio.get_event_loop()
try:
loop.run_until_complete(asyncio.Task(g(f, 2)))
except KeyboardInterrupt:
print('Loop stopped')
Thanks, now I got it. I just couldn't figure out that I have to yield
from the sleep function.
Now putting this into a PeriodicTask class that provides a similar
interface like our callback version, I get:
import asyncio
class PeriodicTask2(object):
def __init__(self, func, interval):
self.func = func
self.interval = interval
self._loop = asyncio.get_event_loop()
def start(self):
self.loop.run_until_complete(asyncio.Task(self._run()))
@asyncio.coroutine
def _run(self):
while True:
yield from asyncio.sleep(self.interval)
self.func()
I don't know if I misunderstood anything, but as a user of this class I
am not able to run two task simultaneously because start() will block.
In the callback version I could instanciate two PeriodicTasks and run
them both at the same time (after a call to loop.run_forever()), which
is actually what I wanted to achieve with this class.
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