diff -Naur gdl-0.9rc2/src/envt.hpp gdl-0.9rc2.new/src/envt.hpp
--- gdl-0.9rc2/src/envt.hpp	2009-01-20 14:33:56.000000000 -0500
+++ gdl-0.9rc2.new/src/envt.hpp	2009-08-25 22:18:44.000000000 -0400
@@ -508,6 +508,8 @@
   void AssureStringScalarPar( SizeT ix, DString& scalar);
 
   // to be extended on demand for other data types  
+  
+  friend class DInterpreter;
 };