1.1 --- a/org/util.org	Sat Feb 04 02:15:32 2012 -0700
     1.2 +++ b/org/util.org	Sat Feb 04 03:29:59 2012 -0700
     1.3 @@ -202,6 +202,19 @@
     1.4    keeping the keys the same."  
     1.5    [f m] (zipmap (keys m) (map f (vals m))))
     1.6  
     1.7 +(defn runonce
     1.8 +  "Decorator.  returns a function which will run only once. 
     1.9 +   Inspired by Halloway's version from Lancet."
    1.10 +  {:author "Robert McIntyre"}
    1.11 +  [function]
    1.12 +  (let [sentinel (Object.) 
    1.13 +	result (atom sentinel)]
    1.14 +    (fn [& args]
    1.15 +       (locking sentinel
    1.16 +	 (if (= @result sentinel) 
    1.17 +	   (reset! result (apply function args)) 
    1.18 +	    @result)))))
    1.19 +
    1.20  
    1.21  #+end_src
    1.22