Fixed bug 2694067.

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@1138 7ec92016-0320-0410-acc4-a06ded1c099a

include/loki/SafeFormat.h

@@ -100,6 +100,21 @@ namespace Loki
 
     template <class Device, class Char>
     struct PrintfState {
+
+        /** This constructor exists only to convert a PrintfState for one device type into a
+         PrintfState for another device type. It is not for public use.
+         */
+        template < class Device2 >
+        PrintfState( Device2 & dev, const Char * format, size_t width, size_t prec,
+            unsigned int flags, LOKI_SAFEFORMAT_SIGNED_LONG result )
+                : device_( dev )
+                , format_( format )
+                , width_( width )
+                , prec_( prec )
+                , flags_( flags )
+                , result_( result ) {
+        }
+
         PrintfState(Device dev, const Char * format)
                 : device_(dev)
                 , format_(format)
@@ -113,6 +128,15 @@ namespace Loki
         ~PrintfState() {
         }
 
+        /** This function converts a PrintfState for one device type into a PrintfState for
+         another device type. It is not for public use.
+         */
+        template < class Device2 >
+        PrintfState< Device2, Char > ChangeDevice( Device2 & device ) const
+        {
+            return PrintfState< Device2, Char >( device, format_, width_, prec_, flags_, result_ );
+        }
+
         #define LOKI_PRINTF_STATE_FORWARD(type) \
             PrintfState& operator()(type par) {\
                 return (*this)(static_cast< LOKI_SAFEFORMAT_UNSIGNED_LONG >(par)); \