--- a/src/core/integer.cc	Sat Mar 01 05:42:14 2008 +0100
+++ b/src/core/integer.cc	Sat Mar 01 19:54:48 2008 +0100
@@ -60,6 +60,9 @@
 	}
       return v->Get ().Get () >= m_minValue && v->Get ().Get() <= m_maxValue;
     }
+    virtual Attribute Create (void) const {
+      return Attribute::Create<IntegerValue> ();
+    }
     int64_t m_minValue;
     int64_t m_maxValue;
   } *checker = new IntegerChecker (min, max);