(defnk new-sandbox
  "Creates a sandbox that evaluates the code string that it gets passed.
   The given namespace will be keeped unless :remember-state is given a
   number greater then zero. If :remember-state >= 1 the namespace will
   be torn down for every call of the sandbox, but functions like def,
   alter, dosync will be 'rememberd' and rerun on the next sandbox call.
   Only remember-state commands are keeped in history, if one command in
   the history causes an exception it is removed."
  [:namespace (gensym "net.licenser.sandbox.box")
   :tester secure-tester
   :timeout *default-sandbox-timeout*
   :context (-> (empty-perms-list) domain context)
   :object-tester default-obj-tester
   :remember-state 0]
  (let [history (atom [])]
    (fn sandbox-executor [form]
      (let [form (dot-replace form)]
	(if (tester form namespace)
	  (thunk-timeout 
	   (fn timeout-box [] 
	     (sandbox 
	      (fn sandbox-jvm-runnable-code []
		(if (not (zero? remember-state))
		  (doseq [d @history]
		    (try
		      (let [r (binding [*read-eval* false *ns* (create-ns namespace) dot (dot-maker object-tester)] (refer 'clojure.core) (eval '(def dot net.licenser.sandbox/dot)) (eval d))]
			(if (coll? r) (doall r) r))
		      (catch Exception e
			(swap! history #(remove (partial = d) %))))))
		(let [r (binding [*read-eval* false *ns* (create-ns namespace) dot (dot-maker object-tester)] (refer 'clojure.core) (eval '(def dot net.licenser.sandbox/dot)) (eval form))]
		  (if (and  (not (zero? remember-state)) (has-state? form))
		    (do
		      (if (>= (count @history) remember-state)
			(swap! history #(conj (rest %) form))
			(swap! history conj form))
		      (remove-ns namespace)))
		    (if (coll? r) (doall r) r))) context)) timeout)
	  (throw (SecurityException. (str "Code did not pass sandbox guidelines:" (pr-str (find-bad-forms tester namespace form))))))))))