Backed out changeset: 83039c25f3cc

This change runs into a bug in visual studio 2005 that I can't seem
to find a way to avoid.  Might try it again later, but for now, I'm backing
it out.

dlib/svm/sparse_vector.h

@@ -216,33 +216,16 @@ namespace dlib
 
     // ------------------------------------------------------------------------------------
 
-
-        namespace impl
-        {
-            // This funny looking thing is here to let us use SFINAE to make the dot()
-            // function below only get selected from the overload resolution order if
-            // it's operating on two sparse vectors.
-            template <typename T, typename U>
-            struct dot_ret_type
-            {
-                typedef T type;
-            };
-        }
-
-        // This funny looking thing is here to let us use SFINAE to make the dot()
-        // function below only get selected from the overload resolution order if
-        // it's operating on two sparse vectors.
-        template <typename T, typename U>
-        typename dlib::sparse_vector::impl::dot_ret_type<typename T::value_type::second_type,typename U::value_type::second_type>::type 
-        dot (
+        template <typename T>
+        typename T::value_type::second_type dot (
             const T& a,
-            const U& b
+            const T& b
         )
         {
             typedef typename T::value_type::second_type scalar_type;
 
             typename T::const_iterator ai = a.begin();
-            typename U::const_iterator bi = b.begin();
+            typename T::const_iterator bi = b.begin();
 
             scalar_type sum = 0;
             while (ai != a.end() && bi != b.end())

dlib/svm/sparse_vector_abstract.h

@@ -152,10 +152,10 @@ namespace dlib
 
     // ----------------------------------------------------------------------------------------
 
-        template <typename T, typename U>
+        template <typename T>
         typename T::value_type::second_type dot (
             const T& a,
-            const U& b
+            const T& b
         );
         /*!
             requires