Selectable queue

Sometimes you'd want to use something like on Queues. If you do some searching for this it turns out that this question has been answered for multiprocessing Queues where you can simply use the real select on the underlying socket (IIRC), but for a good old fashioned Queue you're stuck.

Now it's easy to argue that this isn't that high a need, when I wanted this a while ago it turned out to be surprisingly simple to re-structure the design a little so that I no longer desired a selectable queue. But it's still something that hung around the back of my mind for a while, so I've kept thinking about it. My conclusion for now (which I haven't bothered implementing) is that simply cloning the normal queues but replacing the not_empty and not_full Conditions by Events gives you selectable queues. It changes the semantics slightly, but that doesn't seem harmful. This obviously isn't enough, so the second change to the queue is that you should be allowed to pass in the events to use. And now that you can share the not_full event between two queues you can simply wait on this event and you have your select.

Next time I want this I might actually implement this idea rather then re-design so that I don't want selectable queues anymore.