[Stackless] Google's new Go programming language

[Andrew Dalke]

On Nov 12, 2009, at 9:40 PM, Andrew Francis wrote:
> That said, one feature that would be nice to have in Stackless as a  
> language feature would be select, where one is waiting on multiple  
> channels. Yes this could be built as library but it is not as nice.

One of the Go demos is

func server(op binOp, service chan *request, quit chan bool) {
     for {
         select {
         case req := <-service:
             go run(op, req);  // don't wait for it
         case <-quit:
             return;
         }
     }
}

Doing this in stackless seems complicated. The solution I see would be

def forward_requests(name, from_ch, to_ch):
     for item in from_ch:
         to_ch.send( (name, item) )

common_channel = channel()
tasklet(forward_requests)("req", request, common_channel)
tasklet(forward_requsts)("quit", quit, common_channel)

for tag, item in common_channel():
     if tag == "quit":
         return
     elif tag == "req":
         tasklet(run)(op, req)

This could be wrapped up in a function like, perhaps,

   def select(**kwargs):
     common_channel = channel()
     for name, from_ch in kwargs.items():
         forward_requests(name, from_ch, common_channel)
     return common_channel

making the entire process

for (name, event) in select(quit=quit, req=request)
   if name == "quit":
     return
   elif tag == "req":
     tasklet(run)(op, req)


Is this clean? Elegant? A hack? I don't recall people bringing up the  
need for something like it before.
>

				Andrew
				dalke at dalkescientific.com