Merge branch 'feature/fix-cmake-magic-for-category-interface' into 'master'

[dynamic polymorphism] use #if instead of #ifdef for the guard

See merge request !95

dune/istl/operators.hh

@@ -84,7 +84,7 @@ namespace Dune {
 
     //! Category of the linear operator (see SolverCategory::Category)
     virtual SolverCategory::Category category() const
-#ifdef DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE
+#if DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE
     {
       DUNE_THROW(Dune::Exception,"It is necessary to implement the category method in a derived classes, in the future this method will pure virtual.");
     };

dune/istl/preconditioner.hh

@@ -77,7 +77,7 @@ namespace Dune {
 
     //! Category of the preconditioner (see SolverCategory::Category)
     virtual SolverCategory::Category category() const
-#ifdef DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE
+#if DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE
     {
       DUNE_THROW(Dune::Exception,"It is necessary to implement the category method in a derived classes, in the future this method will pure virtual.");
     }

dune/istl/scalarproducts.hh

@@ -63,9 +63,13 @@ namespace Dune {
 
     //! Category of the scalar product (see SolverCategory::Category)
     virtual SolverCategory::Category category() const
+#if DUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE
     {
       DUNE_THROW(Dune::Exception,"It is necessary to implement the category method in a derived classes, in the future this method will pure virtual.");
     }
+#else
+    = 0;
+#endif
 
     //! every abstract base class has a virtual destructor
     virtual ~ScalarProduct () {}