[Python-ideas] Add a generic async IO poller/reactor to select module

[Terry Reedy]

On 5/24/2012 2:40 PM, Giampaolo Rodolà wrote:

> It's not clear to me what such a PEP should address in particular,
> anyway here's a bunch of semi-random ideas.

I have been reading for perhaps a decade how bad asyncore is. So I  hope 
you stick with trying to thrash out something different, even if the 
discussion gets tedious or contentions.

> === Idea #1 ===
>
> 4 classes (SelectPoller, PollPoller, EpollPoller, KqueuePoller) within
> concurrent.eventloop namespace all sharing the same API:

For new classes, the first question is what concept (and data/function 
grouping) they and their instances represent. As a naive event loop 
user, I might think in terms of event sources (or sets of sources) and 
corresponding handlers. For events generated by 'file' polling, the 
particular method would seem like a secondary issue.

Your proposed classes are named after methods and you give no 
initialization api. This suggests to me that you mean for all files 
being polled by the same method to be grouped together. If so, there 
would only need 0 or 1 instance of each 'class', in while case, they 
could just as well be modules.

In other words, I am unsure what concept these classes would represent. 
I am perhaps thinking at too high a level.

> - register(fd, events, callback)  # callback gets called with events as arg
> - modify(fd, events)
> - unregister(fd)
> - call_later(timeout, callback, errback=None)
> - call_every(timeout, callback, errback=None)
> - poll(timeout=1.0, blocking=True)
> - close()
>
> call_later() and call_every() can return an object having cancel() and
> reset() methods.

-- 
Terry Jan Reedy