diff -r b20777184ba8 -r 22752dd6c693 lemon/graph_adaptor.h
--- a/lemon/graph_adaptor.h	Fri Oct 14 10:58:54 2005 +0000
+++ b/lemon/graph_adaptor.h	Fri Oct 14 11:00:40 2005 +0000
@@ -1526,13 +1526,14 @@
 	else {exit.set(key, val); }
       }
       
-      typename ReferenceMapTraits<NodeImpl>::Reference 
+      typename MapTraits<NodeImpl>::ReturnValue 
       operator[](const Node& key) {
 	if (key.entry) { return entry[key]; }
 	else { return exit[key]; }
       }
 
-      T operator[](const Node& key) const {
+      typename MapTraits<NodeImpl>::ConstReturnValue
+      operator[](const Node& key) const {
 	if (key.entry) { return entry[key]; }
 	else { return exit[key]; }
       }
@@ -1556,13 +1557,14 @@
 	else {bind.set(key.bind, val); }
       }
       
-      typename ReferenceMapTraits<EdgeImpl>::Reference
+      typename MapTraits<EdgeImpl>::ReturnValue
       operator[](const Edge& key) {
 	if ((typename Parent::Edge&)key != INVALID) { return orig[key]; }
 	else {return bind[key.bind]; }
       }
 
-      T operator[](const Edge& key) const {
+      typename MapTraits<EdgeImpl>::ConstReturnValue
+      operator[](const Edge& key) const {
 	if ((typename Parent::Edge&)key != INVALID) { return orig[key]; }
 	else {return bind[key.bind]; }
       }