Johnny, On Tue, Sep 8, 2015 at 11:32 AM, Johnny Wong <zhanlandet...@gmail.com> wrote: > > why " deliver a @b is going to fail " ? 1 and 2 are just two > independent threads , "deliver a 42" will unblock thread 2 , and then > thread 1 will be unblocked . > Thread 1 is waiting on delivering a result to "a", though, which has already happened with the outer (deliver a 42) - one result per promise.
> what is the pointer of function sync-fn ? what is the execution sequence > of functions such as sync-fn,call-servervice, and callback-fn ? > statement "((sync-fn call-service) 8 7) ", where is the callback-fn > parameter ? > After the apply, call-service ends up being invoked as (call-service 8 7 #(deliver result %&)) - the callback-fn is that final anonymous function which delivers the "result" promise a sequence of its arguments (%&). sync-fn is geared towards multiple invocations - a named example may be very slightly clearer: (def call-service-sync (sync-fn call-service)) (call-service-sync 8 7) ;; => (15 1) The sequence is: - Invoke (sync-fn call-service), which returns a wrapper around call-service, using a callback-fn which is internal to the wrapper (consumers of sync-fn are trying to ignore callback-fn) - Invoke the returned function/wrapper with the arguments to the wrapped (call-service) function (8 7), minus callback-fn - The wrapper forwards these arguments to call-service, plus a callback-fn which delivers its arguments to a promise - The wrapper blocks on dereferencing the promise - The outermost caller receives the value delivered to the promise Take care, Moe -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
