From be9d72e6131e50051af412d70f32ac882317df7a Mon Sep 17 00:00:00 2001
From: Simon Praetorius <simon.praetorius@tu-dresden.de>
Date: Thu, 30 Aug 2018 19:15:42 +0200
Subject: [PATCH] Implementation and test of timeseries writer

---
 dune/vtk/vtktimeserieswriter.hh               | 16 ++++-----
 dune/vtk/vtktimeserieswriter.impl.hh          | 20 ++++++++---
 .../writers/vtkunstructuredgridwriter.impl.hh | 10 +++---
 src/benchmark.cc                              |  5 ++-
 src/datacollector.cc                          |  5 ++-
 src/geometrygrid.cc                           |  4 +--
 src/legacyvtkwriter.cc                        |  4 +--
 src/polygongrid.cc                            |  9 ++---
 src/structuredgridwriter.cc                   | 16 ++++-----
 src/test/mixed_element_test.cc                |  9 +++--
 src/test/reader_writer_test.cc                |  9 +++--
 src/timeserieswriter.cc                       | 30 +++++++---------
 src/vtkreader.cc                              | 36 ++++++++++---------
 src/vtkwriter.cc                              | 13 ++++---
 14 files changed, 94 insertions(+), 92 deletions(-)

diff --git a/dune/vtk/vtktimeserieswriter.hh b/dune/vtk/vtktimeserieswriter.hh
index 78feb8f..929d0fd 100644
--- a/dune/vtk/vtktimeserieswriter.hh
+++ b/dune/vtk/vtktimeserieswriter.hh
@@ -1,14 +1,10 @@
 #pragma once
 
-#include <iosfwd>
-#include <map>
 #include <string>
+#include <tuple>
 #include <vector>
 
-#include <dune/common/std/optional.hh>
-
 #include <dune/vtk/filewriter.hh>
-#include <dune/vtk/vtkfunction.hh>
 #include <dune/vtk/vtktypes.hh>
 
 namespace Dune
@@ -16,6 +12,7 @@ namespace Dune
   /// File-Writer for Vtk .vtu files
   template <class VtkWriter>
   class VtkTimeseriesWriter
+      : public FileWriter
   {
   protected:
     using Self = VtkTimeseriesWriter;
@@ -26,13 +23,16 @@ namespace Dune
     template <class... Args, disableCopyMove<Self, Args...> = 0>
     VtkTimeseriesWriter (Args&&... args)
       : vtkWriter_{std::forward<Args>(args)...}
-    {}
+    {
+      assert(vtkWriter_.format_ != Vtk::ASCII && "Timeseries writer requires APPENDED mode");
+    }
 
     /// Write the attached data to the file with \ref Vtk::FormatTypes and \ref Vtk::DataTypes
     void writeTimestep (double time, std::string const& fn);
 
-    // NOTE: requires a aforging call to \ref write
-    void write (std::string const& fn);
+    /// Writes all timesteps to single timeseries file.
+    // NOTE: requires an aforging call to \ref writeTimestep
+    virtual void write (std::string const& fn) override;
 
     /// Attach point data to the writer, \see VtkFunction for possible arguments
     template <class Function, class... Args>
diff --git a/dune/vtk/vtktimeserieswriter.impl.hh b/dune/vtk/vtktimeserieswriter.impl.hh
index cc20ead..224e80f 100644
--- a/dune/vtk/vtktimeserieswriter.impl.hh
+++ b/dune/vtk/vtktimeserieswriter.impl.hh
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <algorithm>
+#include <cstdio>
 #include <iomanip>
 #include <iostream>
 #include <iterator>
@@ -34,7 +35,7 @@ void VtkTimeseriesWriter<W>
 
   if (!initialized_) {
     // write points and cells only once
-    filenameMesh_ = p.string() + ".mesh.data";
+    filenameMesh_ = p.string() + ".mesh.vtkdata";
     std::ofstream file_mesh(filenameMesh_, std::ios_base::ate | std::ios::binary);
 
     if (vtkWriter_.datatype_ == Vtk::FLOAT32)
@@ -45,11 +46,9 @@ void VtkTimeseriesWriter<W>
     auto bs = vtkWriter_.writeCellsAppended(file_mesh);
     blocksize_.insert(blocksize_.end(), bs.begin(), bs.end());
     initialized_ = true;
-
-    std::cout << "blocksize = [" << join(blocksize_.begin(), blocksize_.end()) << "]\n";
   }
 
-  std::string filenameData = p.string() + "_t" + std::to_string(timesteps_.size()) + ".data";
+  std::string filenameData = p.string() + "_t" + std::to_string(timesteps_.size()) + ".vtkdata";
   std::ofstream file_data(filenameData, std::ios_base::ate | std::ios::binary);
 
   for (auto const& v : vtkWriter_.pointData_) {
@@ -73,12 +72,23 @@ template <class W>
 void VtkTimeseriesWriter<W>
   ::write (std::string const& fn)
 {
+  assert( initialized_ );
+  assert( timesteps_.size() < 1000 ); // maximal number of allowed timesteps in timeseries file
+
   auto p = filesystem::path(fn);
   auto name = p.stem();
   p.remove_filename();
   p /= name.string();
-  std::string filename = p.string() + "." + vtkWriter_.getFileExtension();
+  std::string filename = p.string() + ".ts." + vtkWriter_.getFileExtension();
   vtkWriter_.writeTimeseriesFile(filename, filenameMesh_, timesteps_, blocksize_);
+
+  // remove all temporary data files
+  int ec = std::remove(filenameMesh_.c_str());
+  assert(ec == 0);
+  for (auto const& timestep : timesteps_) {
+    ec = std::remove(timestep.second.c_str());
+    assert(ec == 0);
+  }
 }
 
 } // end namespace Dune
diff --git a/dune/vtk/writers/vtkunstructuredgridwriter.impl.hh b/dune/vtk/writers/vtkunstructuredgridwriter.impl.hh
index 5abec03..8488ad2 100644
--- a/dune/vtk/writers/vtkunstructuredgridwriter.impl.hh
+++ b/dune/vtk/writers/vtkunstructuredgridwriter.impl.hh
@@ -197,9 +197,12 @@ void VtkUnstructuredGridWriter<GV,DC>
       << ">\n";
 
   out << "<UnstructuredGrid"
-      << " TimeValues=\"\n";
-  for (auto const& timestep : timesteps)
-    out << timestep.first << "\n";
+      << " TimeValues=\"";
+  {
+    std::size_t i = 0;
+    for (auto const& timestep : timesteps)
+      out << timestep.first << (++i % 6 != 0 ? ' ' : '\n');
+  }
   out << "\">\n";
 
   out << "<Piece"
@@ -249,7 +252,6 @@ void VtkUnstructuredGridWriter<GV,DC>
   out << "</Cells>\n";
 
   const std::size_t shift = offsets[0].size(); // number of blocks to write the grid
-  std::cout << "shift = " << shift << "\n";
 
   // Write data associated with grid points
   out << "<PointData" << this->getNames(pointData_) << ">\n";
diff --git a/src/benchmark.cc b/src/benchmark.cc
index e1d731a..2439c28 100644
--- a/src/benchmark.cc
+++ b/src/benchmark.cc
@@ -61,11 +61,10 @@ template <class GridView>
 void writer_new (GridView const& gridView)
 {
   Timer t;
-  VtkUnstructuredGridWriter<GridView> vtkWriter(gridView);
   for (auto const& test_case : test_cases_new) {
     t.reset();
-    vtkWriter.write("writer_new_" + std::get<0>(test_case) + ".vtu",
-      std::get<1>(test_case), std::get<2>(test_case));
+    VtkUnstructuredGridWriter<GridView> vtkWriter(gridView, std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.write("writer_new_" + std::get<0>(test_case) + ".vtu");
     std::cout << "  time (writer_new_" + std::get<0>(test_case) + ") = " << t.elapsed() << "\n";
   }
 }
diff --git a/src/datacollector.cc b/src/datacollector.cc
index 5864a4f..482f45d 100644
--- a/src/datacollector.cc
+++ b/src/datacollector.cc
@@ -32,14 +32,13 @@ using namespace Dune::Functions;
 template <class DataCollector, class GridView, class Fct1, class Fct2>
 void write_dc (std::string prefix, GridView const& gridView, Fct1 const& fct1, Fct2 const& fct2)
 {
-  VtkUnstructuredGridWriter<GridView, DataCollector> vtkWriter(gridView);
+  VtkUnstructuredGridWriter<GridView, DataCollector> vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
   vtkWriter.addPointData(fct1, "p1");
   vtkWriter.addCellData(fct1, "p0");
   vtkWriter.addPointData(fct2, "q1");
   vtkWriter.addCellData(fct2, "q0");
 
-  vtkWriter.write(prefix + "_" + std::to_string(GridView::dimension) + "d_ascii.vtu",
-    Vtk::ASCII, Vtk::FLOAT32);
+  vtkWriter.write(prefix + "_" + std::to_string(GridView::dimension) + "d_ascii.vtu");
 }
 
 template <class GridView>
diff --git a/src/geometrygrid.cc b/src/geometrygrid.cc
index 8b56ffd..1fe36b3 100644
--- a/src/geometrygrid.cc
+++ b/src/geometrygrid.cc
@@ -53,10 +53,10 @@ void write (std::string prefix, GridView const& gridView)
 
   auto p1Analytic = makeAnalyticGridViewFunction([&c](auto const& x) { return c.dot(x); }, gridView);
 
-  VtkWriter<GridView> vtkWriter(gridView);
+  VtkWriter<GridView> vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
   vtkWriter.addPointData(p1Analytic, "q1");
   vtkWriter.addCellData(p1Analytic, "q0");
-  vtkWriter.write(prefix + "_ascii.vtu", Vtk::ASCII, Vtk::FLOAT32);
+  vtkWriter.write(prefix + "_ascii.vtu");
 }
 
 int main (int argc, char** argv)
diff --git a/src/legacyvtkwriter.cc b/src/legacyvtkwriter.cc
index b001fce..c28688d 100644
--- a/src/legacyvtkwriter.cc
+++ b/src/legacyvtkwriter.cc
@@ -38,7 +38,7 @@ int main(int argc, char** argv)
   std::shared_ptr<VTKFunction<GridView> const> p1FctWrapped(new P1Function(gridView, p1function, "p1"));
 
   using Writer = VtkUnstructuredGridWriter<GridView>;
-  Writer vtkWriter(gridView);
+  Writer vtkWriter(gridView, Vtk::ASCII);
   vtkWriter.addPointData(p1FctWrapped);
-  vtkWriter.write("test_ascii_float32.vtu", Vtk::ASCII);
+  vtkWriter.write("test_ascii_float32.vtu");
 }
diff --git a/src/polygongrid.cc b/src/polygongrid.cc
index fd24fd3..626c339 100644
--- a/src/polygongrid.cc
+++ b/src/polygongrid.cc
@@ -57,7 +57,7 @@ int main(int argc, char** argv)
   GridView gridView = gridPtr->leafGridView();
 
   using Writer = VtkUnstructuredGridWriter<GridView>;
-  Writer vtkWriter(gridView);
+  Writer vtkWriter(gridView, Vtk::ASCII);
   auto p1Analytic = makeAnalyticGridViewFunction([](auto const& x) {
     return std::sin(10*x[0])*std::cos(10*x[1]);
   }, gridView);
@@ -65,10 +65,5 @@ int main(int argc, char** argv)
   vtkWriter.addPointData(p1Analytic, "p1");
   vtkWriter.addCellData(p1Analytic, "p0");
 
-  vtkWriter.write("poly_ascii_float32.vtu", Vtk::ASCII);
-  vtkWriter.write("poly_binary_float32.vtu", Vtk::BINARY);
-  vtkWriter.write("poly_compressed_float32.vtu", Vtk::COMPRESSED);
-  vtkWriter.write("poly_ascii_float64.vtu", Vtk::ASCII, Vtk::FLOAT64);
-  vtkWriter.write("poly_binary_float64.vtu", Vtk::BINARY, Vtk::FLOAT64);
-  vtkWriter.write("poly_compressed_float64.vtu", Vtk::COMPRESSED, Vtk::FLOAT64);
+  vtkWriter.write("poly_ascii_float32.vtu");
 }
diff --git a/src/structuredgridwriter.cc b/src/structuredgridwriter.cc
index 349244a..e28067a 100644
--- a/src/structuredgridwriter.cc
+++ b/src/structuredgridwriter.cc
@@ -45,30 +45,30 @@ void write(std::string prefix, GridView const& gridView)
 
   {
     using Writer = VtkImageDataWriter<GridView>;
-    Writer vtkWriter(gridView);
+    Writer vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
     vtkWriter.addPointData(fct2, "analytic");
-    vtkWriter.write(prefix + "id_ascii_float32.vti", Vtk::ASCII, Vtk::FLOAT32);
+    vtkWriter.write(prefix + "id_ascii_float32.vti");
   }
 
   {
     using Writer = VtkRectilinearGridWriter<GridView>;
-    Writer vtkWriter(gridView);
+    Writer vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
     vtkWriter.addPointData(fct2, "analytic");
-    vtkWriter.write(prefix + "rg_ascii_float32.vtr", Vtk::ASCII, Vtk::FLOAT32);
+    vtkWriter.write(prefix + "rg_ascii_float32.vtr");
   }
 
   {
     using Writer = VtkStructuredGridWriter<GridView>;
-    Writer vtkWriter(gridView);
+    Writer vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
     vtkWriter.addPointData(fct2, "analytic");
-    vtkWriter.write(prefix + "sg_ascii_float32.vts", Vtk::ASCII, Vtk::FLOAT32);
+    vtkWriter.write(prefix + "sg_ascii_float32.vts");
   }
 
   {
     using Writer = VtkUnstructuredGridWriter<GridView>;
-    Writer vtkWriter(gridView);
+    Writer vtkWriter(gridView, Vtk::ASCII, Vtk::FLOAT32);
     vtkWriter.addPointData(fct2, "analytic");
-    vtkWriter.write(prefix + "ug_ascii_float32.vts", Vtk::ASCII, Vtk::FLOAT32);
+    vtkWriter.write(prefix + "ug_ascii_float32.vts");
   }
 }
 
diff --git a/src/test/mixed_element_test.cc b/src/test/mixed_element_test.cc
index 6b15247..6dc61ef 100644
--- a/src/test/mixed_element_test.cc
+++ b/src/test/mixed_element_test.cc
@@ -69,10 +69,9 @@ static TestCases test_cases = {
 template <class GridView>
 void writer_test (GridView const& gridView)
 {
-  VtkUnstructuredGridWriter<GridView> vtkWriter(gridView);
   for (auto const& test_case : test_cases) {
-    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu",
-      std::get<1>(test_case), std::get<2>(test_case));
+    VtkUnstructuredGridWriter<GridView> vtkWriter(gridView, std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu");
   }
 }
 
@@ -81,9 +80,9 @@ void reader_test (Test& test)
 {
   for (auto const& test_case : test_cases) {
     auto grid = VtkReader<Grid>::read("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu");
-    VtkUnstructuredGridWriter<typename Grid::LeafGridView> vtkWriter(grid->leafGridView());
-    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu",
+    VtkUnstructuredGridWriter<typename Grid::LeafGridView> vtkWriter(grid->leafGridView(),
       std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu");
     test.check(compare_files("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu",
                              "/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu"), std::get<0>(test_case));
   }
diff --git a/src/test/reader_writer_test.cc b/src/test/reader_writer_test.cc
index d34cbd8..da3e1a1 100644
--- a/src/test/reader_writer_test.cc
+++ b/src/test/reader_writer_test.cc
@@ -69,10 +69,9 @@ static TestCases test_cases = {
 template <class GridView>
 void writer_test (GridView const& gridView)
 {
-  VtkUnstructuredGridWriter<GridView> vtkWriter(gridView);
   for (auto const& test_case : test_cases) {
-    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu",
-      std::get<1>(test_case), std::get<2>(test_case));
+    VtkUnstructuredGridWriter<GridView> vtkWriter(gridView, std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu");
   }
 }
 
@@ -81,9 +80,9 @@ void reader_test (Test& test)
 {
   for (auto const& test_case : test_cases) {
     auto grid = VtkReader<Grid>::read("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu");
-    VtkUnstructuredGridWriter<typename Grid::LeafGridView> vtkWriter(grid->leafGridView());
-    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu",
+    VtkUnstructuredGridWriter<typename Grid::LeafGridView> vtkWriter(grid->leafGridView(),
       std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.write("/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu");
     test.check(compare_files("/tmp/reader_writer_test_" + std::get<0>(test_case) + ".vtu",
                              "/tmp/reader_writer_test_" + std::get<0>(test_case) + "_2.vtu"));
   }
diff --git a/src/timeserieswriter.cc b/src/timeserieswriter.cc
index 35f2752..2b5f693 100644
--- a/src/timeserieswriter.cc
+++ b/src/timeserieswriter.cc
@@ -12,8 +12,6 @@
 #include <dune/common/exceptions.hh> // We use exceptions
 #include <dune/common/filledarray.hh>
 
-#include <dune/functions/functionspacebases/defaultglobalbasis.hh>
-#include <dune/functions/functionspacebases/lagrangebasis.hh>
 #include <dune/functions/gridfunctions/analyticgridviewfunction.hh>
 #include <dune/grid/yaspgrid.hh>
 
@@ -26,25 +24,23 @@ using namespace Dune::Functions;
 template <class GridView>
 void write (std::string prefix, GridView const& gridView)
 {
-  using namespace BasisFactory;
-  auto basis = makeBasis(gridView, lagrange<1>());
-
-  FieldVector<double,GridView::dimension> c;
-  if (GridView::dimension > 0) c[0] = 11.0;
-  if (GridView::dimension > 1) c[1] = 7.0;
-  if (GridView::dimension > 2) c[2] = 3.0;
-
-  // write analytic function
-  auto p1Analytic = makeAnalyticGridViewFunction([&c](auto const& x) { return c.dot(x); }, gridView);
+  FieldVector<double,GridView::dimension> c{11.0, 7.0, 3.0};
+  auto p1Analytic = makeAnalyticGridViewFunction([&c](auto const& x) -> float { return c.dot(x); }, gridView);
 
   using Writer = VtkUnstructuredGridWriter<GridView>;
-  VtkTimeseriesWriter<Writer> vtkWriter(gridView, Vtk::BINARY, Vtk::FLOAT32);
-  vtkWriter.addPointData(p1Analytic, "q1");
-  vtkWriter.addCellData(p1Analytic, "q0");
+  VtkTimeseriesWriter<Writer> seriesWriter(gridView, Vtk::BINARY, Vtk::FLOAT32);
+  seriesWriter.addPointData(p1Analytic, "q1");
+  seriesWriter.addCellData(p1Analytic, "q0");
+  std::string filename = prefix + "_" + std::to_string(GridView::dimension) + "d_binary32.vtu";
   for (double t = 0.0; t < 5; t += 0.5) {
-    vtkWriter.writeTimestep(t, prefix + "_" + std::to_string(GridView::dimension) + "d_ascii.vtu");
+    seriesWriter.writeTimestep(t, filename);
   }
-  vtkWriter.write(prefix + "_" + std::to_string(GridView::dimension) + "d_ascii.vtu");
+  seriesWriter.write(filename);
+
+  Writer vtkWriter(gridView, Vtk::BINARY, Vtk::FLOAT32);
+  vtkWriter.addPointData(p1Analytic, "q1");
+  vtkWriter.addCellData(p1Analytic, "q0");
+  vtkWriter.write(filename);
 }
 
 int main (int argc, char** argv)
diff --git a/src/vtkreader.cc b/src/vtkreader.cc
index b02fcee..d82e96b 100644
--- a/src/vtkreader.cc
+++ b/src/vtkreader.cc
@@ -37,42 +37,46 @@ int main(int argc, char** argv)
 
     GridView gridView = grid.leafGridView();
 
-    VtkUnstructuredGridWriter<GridView> vtkWriter(gridView);
-    vtkWriter.write("test_ascii_float32.vtu", Vtk::ASCII);
-    vtkWriter.write("test_binary_float32.vtu", Vtk::BINARY);
-    vtkWriter.write("test_compressed_float64.vtu", Vtk::COMPRESSED, Vtk::FLOAT64);
+    VtkUnstructuredGridWriter<GridView> vtkWriter1(gridView, Vtk::ASCII);
+    vtkWriter1.write("test_ascii_float32.vtu");
+
+    VtkUnstructuredGridWriter<GridView> vtkWriter2(gridView, Vtk::BINARY);
+    vtkWriter2.write("test_binary_float32.vtu");
+
+    VtkUnstructuredGridWriter<GridView> vtkWriter3(gridView, Vtk::COMPRESSED, Vtk::FLOAT64);
+    vtkWriter3.write("test_compressed_float64.vtu");
   }
 
   {
     auto gridPtr = VtkReader<GridType>::read("test_ascii_float32.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView());
-    vtkWriter.write("test_ascii_float32_2.vtu", Vtk::ASCII);
+    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView(), Vtk::ASCII);
+    vtkWriter.write("test_ascii_float32_2.vtu");
   }
 
   {
     auto gridPtr = VtkReader<GridType>::read("test_binary_float32.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView());
-    vtkWriter.write("test_ascii_float32_3.vtu", Vtk::ASCII);
+    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView(), Vtk::ASCII);
+    vtkWriter.write("test_ascii_float32_3.vtu");
   }
 
   {
     auto gridPtr = VtkReader<GridType>::read("test_compressed_float64.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView());
-    vtkWriter.write("test_ascii_float64_3.vtu", Vtk::ASCII, Vtk::FLOAT64);
+    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView(), Vtk::ASCII, Vtk::FLOAT64);
+    vtkWriter.write("test_ascii_float64_3.vtu");
   }
 
   {
     auto gridPtr = VtkReader<GridType,ConnectedGridCreator>::read("test_ascii_float32.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView());
-    vtkWriter.write("test_ascii_float32_4.vtu", Vtk::ASCII);
+    VtkUnstructuredGridWriter<GridView> vtkWriter(grid.leafGridView(), Vtk::ASCII);
+    vtkWriter.write("test_ascii_float32_4.vtu");
   }
 
   if (filesystem::exists("paraview_3d.vtu")) {
@@ -81,8 +85,8 @@ int main(int argc, char** argv)
     auto gridPtr = VtkReader<GridType3d>::read("paraview_3d.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView3d> vtkWriter(grid.leafGridView());
-    vtkWriter.write("paraview_3d_ascii.vtu", Vtk::ASCII, Vtk::FLOAT64);
+    VtkUnstructuredGridWriter<GridView3d> vtkWriter(grid.leafGridView(), Vtk::ASCII, Vtk::FLOAT64);
+    vtkWriter.write("paraview_3d_ascii.vtu");
   }
 
   if (filesystem::exists("paraview_2d.vtu")) {
@@ -92,7 +96,7 @@ int main(int argc, char** argv)
     auto gridPtr = VtkReader<GridType2d>::read("paraview_2d.vtu");
     auto& grid = *gridPtr;
 
-    VtkUnstructuredGridWriter<GridView2d> vtkWriter(grid.leafGridView());
-    vtkWriter.write("paraview_2d_ascii.vtu", Vtk::ASCII, Vtk::FLOAT64);
+    VtkUnstructuredGridWriter<GridView2d> vtkWriter(grid.leafGridView(), Vtk::ASCII, Vtk::FLOAT64);
+    vtkWriter.write("paraview_2d_ascii.vtu");
   }
 }
diff --git a/src/vtkwriter.cc b/src/vtkwriter.cc
index b15b5ff..d6819bc 100644
--- a/src/vtkwriter.cc
+++ b/src/vtkwriter.cc
@@ -54,14 +54,13 @@ void write (std::string prefix, GridView const& gridView)
   // write analytic function
   auto p1Analytic = makeAnalyticGridViewFunction([&c](auto const& x) { return c.dot(x); }, gridView);
 
-  VtkWriter<GridView> vtkWriter(gridView);
-  vtkWriter.addPointData(p1Interpol, "p1");
-  vtkWriter.addCellData(p1Interpol, "p0");
-  vtkWriter.addPointData(p1Analytic, "q1");
-  vtkWriter.addCellData(p1Analytic, "q0");
   for (auto const& test_case : test_cases) {
-    vtkWriter.write(prefix + "_" + std::to_string(GridView::dimension) + "d_" + std::get<0>(test_case) + ".vtu",
-      std::get<1>(test_case), std::get<2>(test_case));
+    VtkWriter<GridView> vtkWriter(gridView, std::get<1>(test_case), std::get<2>(test_case));
+    vtkWriter.addPointData(p1Interpol, "p1");
+    vtkWriter.addCellData(p1Interpol, "p0");
+    vtkWriter.addPointData(p1Analytic, "q1");
+    vtkWriter.addCellData(p1Analytic, "q0");
+    vtkWriter.write(prefix + "_" + std::to_string(GridView::dimension) + "d_" + std::get<0>(test_case) + ".vtu");
   }
 }
 
-- 
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