Make dispatch async.

WARNING: not tested.

project.clj

@@ -4,6 +4,7 @@
 
   :dependencies [[org.clojure/clojure "1.6.0"]
                  [org.clojure/clojurescript "0.0-2371"]
+                 [org.clojure/core.async "0.1.346.0-17112a-alpha" :scope "provided"]
                  [reagent "0.4.3"]
                  [historian "1.0.7"]]
 

src/re_frame/handlers.cljs

@@ -1,8 +1,12 @@
 (ns re-frame.handlers
+  (:require-macros [cljs.core.async.macros :refer [go-loop]])
   (:require [re-frame.db :refer [app-db]]
-            [re-frame.utils :refer [first-in-vector]]))
+            [re-frame.utils :refer [first-in-vector]]
+            [cljs.core.async :refer [chan put! <!]]))
 
 
+;; -- register of handlers ------------------------------------------------------------------------
+
 (def ^:private id->fn  (atom {}))
 
 
@@ -15,17 +19,36 @@
          assoc event-id handler-fn))
 
 
+;; -- dispatching and routing ---------------------------------------------------------------------
+
+(def ^:private dispatch-chan  (chan))
+
 (defn dispatch
-  "reagent components handle events by calling this function.
+  "reagent components send events by calling this function.
   Usage example:
      (dispatch [:delete-item 42])"
   [event-v]
-  (let [event-id    (first-in-vector event-v)
-        handler-fn  (get @id->fn event-id)]
-    (assert (not (nil? handler-fn)) (str "No event handler registered for event: " event-id ))
-    (handler-fn app-db event-v)))
+  (assert (some? event-v))         ;; nil would close the channel
+  (put! dispatch-chan event-v))
 
 
+(defn- router
+  "route an event, arriving on the dispatch channel, to the right handler"
+  []
+  (go-loop []
+      (let [event-v     (<! dispatch-chan)
+            event-id    (first-in-vector event-v)
+            handler-fn  (get @id->fn event-id)]
+        (assert (not (nil? handler-fn)) (str "No event handler registered for event: " event-id ))
+        (handler-fn app-db event-v)
+        (recur))))
+
+(router)  ;; run the router loop it
+
+
+;; -- helper --------------------------------------------------------------------------------------
+
+;; TODO: this has to go.
 (defn transaction!
   "A helper fucntion to be used when writting event handlers.
   Allows a handler to perform an atomic modification of the atom.