simplify choice of data writer.

dune/fem-dg/algorithm/base.hh

@@ -33,11 +33,6 @@ namespace Fem
       ss << name << loop;
       loop_ = ss.str();
     }
-    explicit EocDataOutputParameters(const std::string& name) {
-      std::stringstream ss;
-      ss << name;
-      loop_ = ss.str();
-    }
     EocDataOutputParameters(const EocDataOutputParameters& other)
     : loop_(other.loop_) {}
 
@@ -186,13 +181,8 @@ namespace Fem
     GridType& grid = algorithm.grid();
     auto dataTup = algorithm.dataTuple() ;
 
-    typedef typename Algorithm::DataWriterHandlerType DataWriterHandlerType;
-    DataWriterHandlerType dataWriter( grid, "" );
-    // initialize data writer with output path and data tuple
-    {
-      EocDataOutputParameters param( algorithm.problem().dataPrefix() );
-      dataWriter.init( dataTup, param );
-    }
+    typedef typename Algorithm::DataWriterHandlerType::template DataOutput< GridType, decltype( dataTup ) > ::Type DataOutputType;
+    DataOutputType dataOutput( grid, dataTup );
 
     // initialize FemEoc if eocSteps > 1
     EocParametersType& eocParam( algorithm.eocParams() );
@@ -234,7 +224,7 @@ namespace Fem
       }
 
       // write eoc step
-      dataWriter.step( eocloop );
+      dataOutput.writeData( eocloop );
 
       // Refine the grid for the next EOC Step. If the scheme uses adaptation,
       // the refinement level needs to be set in the algorithms' initialize method.

dune/fem-dg/algorithm/handler/datawriter.hh

@@ -23,6 +23,12 @@ namespace Fem
   public:
     typedef DataWriter< GridImp, IOTupleImp >       DataWriterType;
 
+    template <class Grid, class DataTuple>
+    struct DataOutput
+    {
+      typedef Dune::Fem::DataWriter< Grid, DataTuple > Type;
+    };
+
 
     DefaultDataWriterHandler( const GridImp& grid, const std::string keyPrefix = "" )
       : dataTuple_(),
@@ -38,13 +44,6 @@ namespace Fem
       dataWriter_.reset( new DataWriterType( grid_, dataTuple_, tp, param ) );
     }
 
-    template< class DataTupleImp, class ParameterType >
-    void init( DataTupleImp dataTup, ParameterType& param  )
-    {
-      dataTuple_ = dataTup;
-      dataWriter_.reset( new DataWriterType( grid_, dataTuple_, param ) );
-    }
-
 
     //template< class InDiscreteFunction, class OutDiscreteFunction, class ... Args >
     //void preWriteData( const InDiscreteFunction& in, OutDiscreteFunction* out, Args& ... args )
@@ -74,15 +73,6 @@ namespace Fem
       }
     }
 
-    void step( const int eocStep )
-    {
-      if( dataWriter_ )
-      {
-        dataWriter_->writeData( eocStep );
-      }
-    }
-
-
     private:
     IOTupleImp             dataTuple_;
     std::unique_ptr< DataWriterType > dataWriter_;
@@ -95,6 +85,11 @@ namespace Fem
   class NoDataWriterHandler
   {
     public:
+    template <class Grid, class DataTuple>
+    struct DataOutput
+    {
+      typedef Dune::Fem::DataOutput< Grid, DataTuple > Type;
+    };
 
     template< class ... Args >
     NoDataWriterHandler( Args&& ... )