You want handle-evt
On Thu, Dec 13, 2012 at 3:27 PM, Ray Racine <ray.rac...@gmail.com> wrote:
> Using a Place or a Place-Channel as a sync event returns the value of a
> place-channel-get and not the Place itself.
>
> Most events return the actual `thing' which one sync'd on. This is not true
> with places and channels, one gets the message itself.
I don't think it's true of "most" events. Other channels and some
ports do the same thing.
>
> The conundrum is identification of which Place / Place-Channel actually
> fired. Places themselves have no real mechanism supporting GUID labeling or
> even simple naming/labeling. There is no (place-name my-place) or ability
> to assign an identifier upon creation. There is documented support for
> Place and Place-Channel equality. So one can work around all this at the
> app code level, i.e. implement their own labeling system for Places.
>
> However assuming a roll your own labeling system there is still the
> anonymity of a place / place-channel when used as a sync event issue.
>
> (let ((msg (sync pl-1 pl-2 pl-3))))
> ;; no idea from which place msg came from, unless explicitly recorded in
> the msg itself.
> ;; e.g. (Msg-sender msg) -> my home brewed Place-GUID
>
> Compare and contrast with ports used as an event. A port used as a sync
> event results in the port itself upon which one can do whatever this
> knowledge. For example, I might opt *not* to read the port as this time,
> even unilaterally close it without reading.
>
> Consider the following parallel, asynchronous request/response idiom.
>
> Given N request msgs and P places, issue one request message per ready
> place. (Ready in the sense it is not processing a request.)
>
> I want something like
>
> (let loop ((msgs ...))
> ...
> (let ((ready-place (sync p1 p2 p3)))
> (process-response (place-channel-get ready-place))
> (process-request ready-place (car msgs))
> (loop (cdr msgs))
(let loop ((msgs ...))
(apply sync (map (lambda (ready-place)
(handle-evt ready-place
(lambda (response)
(p-r response) (p-rq ready-p (car ..)) (loop ...)
) ..... )
Jay
> How would one approach something like this given `sync' not returning the
> ready place but the received msg from some anonymous place which was ready.
>
>
>
> Thanks,
>
> Ray
>
>
>
>
>
>
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--
Jay McCarthy <j...@cs.byu.edu>
Assistant Professor / Brigham Young University
http://faculty.cs.byu.edu/~jay
"The glory of God is Intelligence" - D&C 93
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