--- boost/proto/debug-1.44.0.hpp	2010-06-11 00:03:27.000000000 +0900
+++ boost/proto/debug.hpp	2010-11-30 11:32:30.000000000 +0900
@@ -84,22 +84,41 @@
 
     namespace hidden_detail_
     {
-        struct ostream_wrapper
-        {
-            ostream_wrapper(std::ostream &sout)
-              : sout_(sout)
-            {}
+      struct yes_type { char x; };
+      struct no_type  { yes_type x[2]; };
 
-            std::ostream &sout_;
-        };
+      no_type has_ostream_shift(...);
 
-        template<typename Tag>
-        std::ostream &operator <<(ostream_wrapper sout_wrap, Tag const &)
-        {
-            return sout_wrap.sout_ << typeid(Tag).name();
-        }
+      template<class T>
+      typename boost::enable_if_c<
+          sizeof(*(std::ostream*)NULL << *(T*)NULL)
+        , yes_type >::type
+      has_ostream_shift(const T&);
+
+      template<bool has>
+      struct Out
+      {
+        template<class T> static void out( std::ostream& os, const T& x );
+      };
+
+      template<> template<class T> inline
+      void Out<true>::out( std::ostream& os, const T& x )
+      {
+        os << x;
+      }
+
+      template<> template<class T> inline
+      void Out<false>::out( std::ostream& os, const T& x )
+      {
+        os << typeid(T).name();
+      }
+
+      template<class T> inline
+      void out( std::ostream& os, const T& x )
+      {
+        Out< sizeof(has_ostream_shift(*(T*)NULL)) == sizeof(yes_type) >::out( os, x );
+      }
     }
-
     namespace functional
     {
         /// \brief Pretty-print a Proto expression tree.
@@ -139,20 +158,22 @@
             template<typename Expr>
             void impl(Expr const &expr, mpl::long_<0>) const
             {
-                using namespace hidden_detail_;
                 typedef typename tag_of<Expr>::type tag;
                 this->sout_ << std::setw(this->depth_) << (this->first_? "" : ", ");
-                this->sout_ << tag() << "(" << proto::value(expr) << ")\n";
+                hidden_detail_::out( this->sout_, tag() );
+                this->sout_ << "(";
+                hidden_detail_::out( this->sout_, proto::value(expr) );
+                this->sout_ << ")\n";
                 this->first_ = false;
             }
 
             template<typename Expr, typename Arity>
             void impl(Expr const &expr, Arity) const
             {
-                using namespace hidden_detail_;
                 typedef typename tag_of<Expr>::type tag;
                 this->sout_ << std::setw(this->depth_) << (this->first_? "" : ", ");
-                this->sout_ << tag() << "(\n";
+                hidden_detail_::out( this->sout_, tag() );
+                this->sout_ << "(\n";
                 display_expr display(this->sout_, this->depth_ + 4);
                 fusion::for_each(expr, display);
                 this->sout_ << std::setw(this->depth_) << "" << ")\n";