2 files changed, 25 insertions, 4 deletions
diff --git a/src/clj/clojure/core_deftype.clj b/src/clj/clojure/core_deftype.clj
index 0a90356e..f18b690f 100644
--- a/src/clj/clojure/core_deftype.clj
+++ b/src/clj/clojure/core_deftype.clj
@@ -18,7 +18,6 @@
                (vector name (vec (map tag args)) (tag name)))
         cname (with-meta (symbol (str *ns* "." name)) (meta name))]
     `(do (gen-interface :name ~cname :methods ~(vec (map psig sigs)))
-         (ns-unmap (find-ns '~(ns-name *ns*)) '~name)
          (import ~cname))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;; reify/deftype ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -289,7 +288,6 @@
        ~(emit-defrecord name gname (vec hinted-fields) (vec interfaces) methods)
        (defmethod print-method ~classname [o# w#]
            ((var print-defrecord) o# w#))
-       (ns-unmap (find-ns '~(ns-name *ns*)) '~name)
        (import ~classname)
        #_(defn ~name
          ([~@fields] (new ~classname ~@fields nil nil))
@@ -379,7 +377,6 @@
         fields (vec (map #(with-meta % nil) fields))]
     `(do
        ~(emit-deftype* name gname (vec hinted-fields) (vec interfaces) methods)
-       (ns-unmap (find-ns '~(ns-name *ns*)) '~name)
        (import ~classname))))
 
 
diff --git a/src/jvm/clojure/lang/Namespace.java b/src/jvm/clojure/lang/Namespace.java
index 09d87037..85505d91 100644
--- a/src/jvm/clojure/lang/Namespace.java
+++ b/src/jvm/clojure/lang/Namespace.java
@@ -86,6 +86,30 @@ Object reference(Symbol sym, Object val){
 	throw new IllegalStateException(sym + " already refers to: " + o + " in namespace: " + name);
 }
 
+public static boolean areDifferentInstancesOfSameClassName(Class cls1, Class cls2) {
+    return (cls1 != cls2) && (cls1.getName().equals(cls2.getName()));
+}
+
+Class referenceClass(Symbol sym, Class val){
+    if(sym.ns != null)
+        {
+        throw new IllegalArgumentException("Can't intern namespace-qualified symbol");
+        }
+    IPersistentMap map = getMappings();
+    Class c = (Class) map.valAt(sym);
+    while((c == null) || (areDifferentInstancesOfSameClassName(c, val)))
+        {
+        IPersistentMap newMap = map.assoc(sym, val);
+        mappings.compareAndSet(map, newMap);
+        map = getMappings();
+        c = (Class) map.valAt(sym);
+        }
+    if(c == val)
+        return c;
+
+    throw new IllegalStateException(sym + " already refers to: " + c + " in namespace: " + name);
+}
+
 public void unmap(Symbol sym) throws Exception{
 	if(sym.ns != null)
 		{
@@ -101,7 +125,7 @@ public void unmap(Symbol sym) throws Exception{
 }
 
 public Class importClass(Symbol sym, Class c){
-	return (Class) reference(sym, c);
+	return referenceClass(sym, c);
 
 }