Fixed variable capture

ndpar · Nov 25, 2012 · 46148ef · 46148ef
1 parent c05e663
commit 46148ef
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Showing 2 changed files with 13 additions and 4 deletions.
diff --git a/src/dojo/handler.clj b/src/dojo/handler.clj
@@ -1,10 +1,11 @@
 (ns dojo.handler)
 
 (defmacro handler [name args & body]
-  `(fn [~'msg]
-     (let [~@(mapcat (fn [x] [x `(get ~'msg ~(keyword x))]) args)]
-       (when (or ~@args)
-         ~@body))))
+  (let [msg (gensym)]
+    `(fn [~msg]
+       (let [~@(mapcat (fn [x] [x `(get ~msg ~(keyword x))]) args)]
+         (when (or ~@args)
+           ~@body)))))
 
 (defmacro build-handlers [& body]
   `(defn- handlers []

diff --git a/test/dojo/handler_test.clj b/test/dojo/handler_test.clj
@@ -8,3 +8,11 @@
   (is (= ["Document:A:null" "Note:B:null" "Alert:A:B"] (on-message {:id 1 :a "A" :b "B"})))
   (is (= ["Document:A:C" "Note:null:C" "Alert:A:null"] (on-message {:id 2 :a "A" :c "C"})))
   (is (= ["Document:A:C" "Note:B:C" "Alert:A:B"] (on-message {:id 2 :a "A" :b "B" :c "C"}))))
+
+(deftest var-capturing-test
+  (let [msg-handler (handler msg [msg something]
+                             (format "Msg:%s:%s" msg something))
+        x-handler (handler x [x something]
+                           (format "X:%s:%s" x something))]
+    (is (= "Msg:3:5" (msg-handler {:msg 3 :something 5})))
+    (is (= "X:3:5" (x-handler {:x 3 :something 5})))))