pass by value -> pass by reference

src/mysolver.cc

@@ -13,7 +13,7 @@
 template <int dim, class MatrixType, class VectorType, class GridType,
           class BlockProblemType>
 MySolver<dim, MatrixType, VectorType, GridType, BlockProblemType>::MySolver(
-    Dune::ParameterTree parset, int refinements, double solver_tolerance,
+    Dune::ParameterTree const &parset, int refinements, double solver_tolerance,
     GridType const &grid, Dune::BitSetVector<dim> const &ignoreNodes)
     : baseEnergyNorm(linearBaseSolverStep),
       linearBaseSolver(&linearBaseSolverStep,

src/mysolver.hh

@@ -22,8 +22,9 @@ class MySolver {
                                             NonlinearSmootherType> SolverType;
 
 public:
-  MySolver(Dune::ParameterTree parset, int refinements, double solver_tolerance,
-           GridType const &grid, Dune::BitSetVector<dim> const &ignoreNodes);
+  MySolver(Dune::ParameterTree const &parset, int refinements,
+           double solver_tolerance, GridType const &grid,
+           Dune::BitSetVector<dim> const &ignoreNodes);
 
   ~MySolver();