Re: Idea for an event loop library

[Graham Wakefield <wakefield@...>]

Another possible source of inspiration:
http://lua-av.mat.ucsb.edu/blog/?p=137

function clockprinter(name, period) 
  while true do
    print(now(), name) 
    wait(period)
  end
end

go(clockprinter, "T O C K!", 4) 
go(clockprinter, "...tick...", 1)

We aimed for a concise syntax and generalizable capability. The default scheduler is driven from a timer, but other schedulers can be created and driven arbitrarily. Coroutines can be scheduled against timeouts or string-identifed events. 

It should be easy to implement this on top of an arbitrary event loop. 
I can turn this into a stand-alone module if there is interest.

On May 10, 2012, at 4:45 AM, Valerio Schiavoni wrote:

> Hello Rob,
> 
> take a look at what we have inside the Splay runtime, as it sounds very close to that:
> 
> http://www.splay-project.org/manual#events
> 
> best,
> valerio
> 
> On Wed, May 9, 2012 at 1:22 PM, Rob Hoelz <rob@hoelz.ro> wrote:
> Hello list,
> 
> I've been meaning to write a new event library for a while, but I
> thought I'd throw the idea at the list first to see if it has merit.
> 
> Basically, I want to create an event library for Lua that sits on top
> of another event library (luaevent for now, but I would probably make
> the system flexible enough for a different library should that be
> desired).  It would provide a simpler interface for events, so you could
> do something like this:
> 
>    local w = ev:timer {
>      interval = 1,
>      callback = function()
>        print 'One second has passed!'
>      end
>    }
> 
> However, that part is just the gravy.  The point of doing a whole new
> library would be to make the entire thing coroutine-based.  Think of it
> like Copas, but applied to generic events instead of just TCP/IP
> sockets.  So let's say I wanted to print 'hello' a second after a user
> clicked a button in a GUI.  I could do something like this:
> 
>  -- this assumes that the GUI plays nicely with the event loop
>  button:onclick(function()
>    ev:sleep(1)
>    print 'hi'
>  end)
> 
> and other events would continue to fire while the button handler is
> sleeping.  Also, you could write a timer-based event like this:
> 
> ev:go(function()
>  while true do
>    ev:sleep(1)
>    print 'waking up!'
>  end
> end)
> 
> The library would also provide other operations for waiting for an event
> to happen.
> 
> So, what do you all think?  Does this idea sound cool to you too, or
> does it sound useless/dumb/too magical/etc?
> 
> -Rob
> 
>