Mire: introduce move-between-refs

apauley · May 26, 2010 · e5b892d · e5b892d
1 parent c028a29
commit e5b892d
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Showing 2 changed files with 11 additions and 3 deletions.
diff --git a/PeepCode/Clojure/mire/src/mire/rooms.clj b/PeepCode/Clojure/mire/src/mire/rooms.clj
@@ -1,4 +1,5 @@
-(ns mire.rooms)
+(ns mire.rooms
+  (:use [mire util]))
 
 (declare rooms)
 
@@ -33,6 +34,7 @@
 
 (defn move-player-to [target]
   (dosync
-   (alter (:inhabitants (current-room)) disj player-name)
-   (alter (:inhabitants target)         conj player-name)
+   (move-between-refs player-name
+                      (:inhabitants (current-room))
+                      (:inhabitants target))
    (ref-set *current-room* target)))
diff --git a/PeepCode/Clojure/mire/src/mire/util.clj b/PeepCode/Clojure/mire/src/mire/util.clj
@@ -3,3 +3,9 @@
 (defn print-flush [text]
   (print text)
   (flush))
+
+(defn move-between-refs
+  "Move one instance of obj between from and to. Must be called in a transaction."
+  [obj from to]
+  (alter from disj obj)
+  (alter to conj obj))