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.