Made the reduced trainers copyable so that they can be used

with the threaded cross validation functions.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%402448

dlib/svm/reduced.h

@@ -31,6 +31,9 @@ namespace dlib
         typedef typename trainer_type::mem_manager_type mem_manager_type;
         typedef typename trainer_type::trained_function_type trained_function_type;
 
+        reduced_decision_function_trainer (
+        ) :num_sv(0) {}
+
         reduced_decision_function_trainer (
             const trainer_type& trainer_,
             const unsigned long num_sv_ 
@@ -61,6 +64,11 @@ namespace dlib
             const in_scalar_vector_type& y
         ) const
         {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(num_sv > 0,
+                        "\t reduced_decision_function_trainer::train(x,y)"
+                        << "\n\t You have tried to use an uninitialized version of this object"
+                        << "\n\t num_sv: " << num_sv );
             return do_train(vector_to_matrix(x), vector_to_matrix(y));
         }
 
@@ -142,8 +150,8 @@ namespace dlib
 
     // ------------------------------------------------------------------------------------
 
-        const trainer_type& trainer;
-        const unsigned long num_sv; 
+        trainer_type trainer;
+        unsigned long num_sv; 
 
 
     }; // end of class reduced_decision_function_trainer
@@ -181,6 +189,7 @@ namespace dlib
         typedef typename trainer_type::mem_manager_type mem_manager_type;
         typedef typename trainer_type::trained_function_type trained_function_type;
 
+        reduced_decision_function_trainer2 () : num_sv(0) {}
         reduced_decision_function_trainer2 (
             const trainer_type& trainer_,
             const long num_sv_,
@@ -216,6 +225,11 @@ namespace dlib
             const in_scalar_vector_type& y
         ) const
         {
+            // make sure requires clause is not broken
+            DLIB_ASSERT(num_sv > 0,
+                        "\t reduced_decision_function_trainer2::train(x,y)"
+                        << "\n\t You have tried to use an uninitialized version of this object"
+                        << "\n\t num_sv: " << num_sv );
             return do_train(vector_to_matrix(x), vector_to_matrix(y));
         }
 
@@ -571,9 +585,9 @@ namespace dlib
 
     // ------------------------------------------------------------------------------------
 
-        const trainer_type& trainer;
-        const long num_sv;
-        const double eps;
+        trainer_type trainer;
+        long num_sv;
+        double eps;
 
 
     }; // end of class reduced_decision_function_trainer2

dlib/svm/reduced_abstract.h

@@ -41,6 +41,15 @@ namespace dlib
         typedef typename trainer_type::mem_manager_type mem_manager_type;
         typedef typename trainer_type::trained_function_type trained_function_type;
 
+        reduced_decision_function_trainer (
+        );
+        /*!
+            ensures
+                - This object is in an uninitialized state.  You must
+                  construct a real one with the other constructor and assign it
+                  to this instance before you use this object.
+        !*/
+
         reduced_decision_function_trainer (
             const trainer_type& trainer,
             const unsigned long num_sv 
@@ -140,6 +149,15 @@ namespace dlib
         typedef typename trainer_type::mem_manager_type mem_manager_type;
         typedef typename trainer_type::trained_function_type trained_function_type;
 
+        reduced_decision_function_trainer2 (
+        );
+        /*!
+            ensures
+                - This object is in an uninitialized state.  You must
+                  construct a real one with the other constructor and assign it
+                  to this instance before you use this object.
+        !*/
+
         reduced_decision_function_trainer2 (
             const trainer_type& trainer,
             const unsigned long num_sv,