FunctionSpace Reference is cocst.

Next the one who changes some features in base class please check all
how big this change is.

[[Imported from SVN: r1684]]

fem/discreteoperatorimp.hh

@@ -108,7 +108,7 @@ namespace Dune {
       typedef typename DFDomainType::FunctionSpace FunctionSpaceType;
       typedef typename FunctionSpaceType::GridType GridType;
       // the corresponding grid
-      FunctionSpaceType & functionSpace_= dest.getFunctionSpace();
+      const FunctionSpaceType & functionSpace_= dest.getFunctionSpace();
       GridType &grid = functionSpace_.getGrid();
 
       if(leaf_)