diff --git a/dune/gmsh4/reader.hh b/dune/gmsh4/reader.hh
index c87b16b91819566dff0b87e18f0c2a58d197b9d4..46e1817fa0bcc02bd70ab8ad021aacc9b0c9fb3f 100644
--- a/dune/gmsh4/reader.hh
+++ b/dune/gmsh4/reader.hh
@@ -134,6 +134,7 @@ namespace Dune
 
     void readString(std::istream& stream, std::string& name)
     {
+      DUNE_THROW(Dune::NotImplemented, "Method readString() not yet implemented");
       name = "Hallo";
     }
 
diff --git a/dune/gmsh4/utility/filesystem.cc b/dune/gmsh4/utility/filesystem.cc
index fd738cfb7169c51792766c51e041ab95c64bd972..7ba4f015d3c507d06fa34c51bd7eb049108185b3 100644
--- a/dune/gmsh4/utility/filesystem.cc
+++ b/dune/gmsh4/utility/filesystem.cc
@@ -21,174 +21,171 @@
 template <class... Args>
 void inline _ignore_(Args&&...) {}
 
-namespace Dune
+namespace Dune {
+namespace Gmsh4 {
+
+std::string Path::string() const
 {
-  namespace Gmsh4
-  {
+  if (empty())
+    return ".";
 
-    std::string Path::string() const
-    {
-      if (empty())
-        return ".";
+  auto it = begin();
+  auto result = *it;
+  for (++it; it != end(); ++it)
+    result += preferredSeparator + *it;
+  return result;
+}
 
-      auto it = begin();
-      auto result = *it;
-      for (++it; it != end(); ++it)
-        result += preferred_separator + *it;
-      return result;
-    }
 
+void Path::split(std::string p)
+{
+  std::string separators = "/\\";
+  bool relative = true;
 
-    void Path::split(std::string p)
-    {
-      std::string separators = "/\\";
-      bool relative = true;
-
-      Gmsh4::trim(p);
-      Gmsh4::split(p.begin(), p.end(), separators.begin(), separators.end(),
-        [this,&relative](auto first, auto end)
-        {
-          auto token = std::string(first, end);
-
-          if ((!token.empty() && token != "." && token != "..") || (token.empty() && this->empty())) {
-            this->push_back(token);
-            relative = false;
-          } else if (token == "..") {
-            if (relative || this->empty()) {
-              this->push_back(token);
-            }
-            else {
-              this->pop_back();
-            }
-          }
-        });
-    }
-
-
-    Path Path::stem() const
+  trim(p);
+  Dune::Vtk::split(p.begin(), p.end(), separators.begin(), separators.end(),
+    [this,&relative](auto first, auto end)
     {
-      auto f = filename().string();
-      auto pos = f.find_last_of('.');
-      if (f == "." || f == ".." || pos == std::string::npos)
-        return {f};
-      else
-        return {f.substr(0,pos)};
-    }
+      auto token = std::string(first, end);
+
+      if ((!token.empty() && token != "." && token != "..") || (token.empty() && this->empty())) {
+        this->push_back(token);
+        relative = false;
+      } else if (token == "..") {
+        if (relative || this->empty()) {
+          this->push_back(token);
+        }
+        else {
+          this->pop_back();
+        }
+      }
+    });
+}
 
 
-    Path Path::extension() const
-    {
-      auto f = filename().string();
-      auto pos = f.find_last_of('.');
-      if (f == "." || f == ".." || pos == std::string::npos)
-        return {};
-      else
-        return {f.substr(pos)};
-    }
+Path Path::stem() const
+{
+  auto f = filename().string();
+  auto pos = f.find_last_of('.');
+  if (f == "." || f == ".." || pos == std::string::npos)
+    return {f};
+  else
+    return {f.substr(0,pos)};
+}
 
 
-    bool Path::is_absolute(std::string p)
-    {
-      if (p[0] == '/')
-        return true;
+Path Path::extension() const
+{
+  auto f = filename().string();
+  auto pos = f.find_last_of('.');
+  if (f == "." || f == ".." || pos == std::string::npos)
+    return {};
+  else
+    return {f.substr(pos)};
+}
 
-      // c:\ or z:/
-      if (std::isalpha(p[0]) && p[1] == ':' && (p[2] == '/' || p[2] == '\\'))
-        return true;
 
-      return false;
-    }
+bool Path::isAbsolute(std::string p)
+{
+  if (p[0] == '/')
+    return true;
 
+  // c:\ or z:/
+  if (std::isalpha(p[0]) && p[1] == ':' && (p[2] == '/' || p[2] == '\\'))
+    return true;
 
-    Path& Path::operator/=(Path const& p)
-    {
-      insert(end(), p.begin(), p.end());
-      original += preferred_separator + p.original;
-      return *this;
-    }
+  return false;
+}
 
 
-    bool Path::is_file() const
-    {
-      std::string p = this->string();
-      struct stat info;
-      return stat(p.c_str(), &info) == 0 && (info.st_mode & S_IFREG) != 0;
-    }
+Path& Path::operator/=(Path const& p)
+{
+  insert(end(), p.begin(), p.end());
+  original += preferredSeparator + p.original;
+  return *this;
+}
 
 
-    bool Path::is_directory() const
-    {
-      std::string p = this->string();
-      struct stat info;
-      return stat(p.c_str(), &info) == 0 && (info.st_mode & S_IFDIR) != 0;
-    }
+bool Path::isFile() const
+{
+  std::string p = this->string();
+  struct stat info;
+  return stat(p.c_str(), &info) == 0 && (info.st_mode & S_IFREG) != 0;
+}
 
 
-    Path current_path()
-    {
-      char cwd_[FILENAME_MAX];
-      _ignore_(GET_CURRENT_DIR(cwd_, sizeof(cwd_)));
-      std::string cwd(cwd_);
-      return { Gmsh4::trim(cwd) };
-    }
+bool Path::isDirectory() const
+{
+  std::string p = this->string();
+  struct stat info;
+  return stat(p.c_str(), &info) == 0 && (info.st_mode & S_IFDIR) != 0;
+}
 
 
-    bool exists(Path const& p)
-    {
-      return p.is_file() || p.is_directory();
-    }
+Path currentPath()
+{
+  char cwd_[FILENAME_MAX];
+  _ignore_(GET_CURRENT_DIR(cwd_, sizeof(cwd_)));
+  std::string cwd(cwd_);
+  return { trim(cwd) };
+}
 
 
-    bool create_directories(Path const& p)
-    {
-      if (p.is_directory())
-        return true;
-
-      auto parent = p.parent_path();
-      if (!parent.empty() && !parent.is_directory())
-        create_directories(parent);
-
-    #ifdef _WIN32
-      int ret = _mkdir(p.string().c_str());
-    #else
-      mode_t mode = 0755;
-      int ret = mkdir(p.string().c_str(), mode);
-    #endif
-      if (ret == 0)
-        return true;
-
-      switch (errno)
-      {
-        case ENOENT:
-          std::cerr << "parent didn't exist. Should not happen, since parent directory created before!\n";
-          std::abort();
-          return false;
-          break;
-        case EEXIST:
-          return true;
-          break;
-        default:
-          return false;
-      }
-    }
+bool exists(Path const& p)
+{
+  return p.isFile() || p.isDirectory();
+}
 
-    Path relative(Path const& a, Path const& b)
-    {
-      // find common base path
-      auto a_it = a.begin();
-      auto b_it = b.begin();
-      for (; a_it != a.end() && b_it != b.end(); ++a_it, ++b_it) {
-        if (*a_it != *b_it)
-          break;
-      }
 
-      // combine remaining parts of a to result path
-      Path rel(".");
-      for (; a_it != a.end(); ++a_it)
-        rel /= *a_it;
+bool createDirectories(Path const& p)
+{
+  if (p.isDirectory())
+    return true;
+
+  auto parent = p.parentPath();
+  if (!parent.empty() && !parent.isDirectory())
+    createDirectories(parent);
 
-      return rel;
-    }
+#ifdef _WIN32
+  int ret = _mkdir(p.string().c_str());
+#else
+  mode_t mode = 0755;
+  int ret = mkdir(p.string().c_str(), mode);
+#endif
+  if (ret == 0)
+    return true;
 
-  } // end namespace Gmsh4
-} // end namespace Dune
+  switch (errno)
+  {
+    case ENOENT:
+      std::cerr << "parent didn't exist. Should not happen, since parent directory created before!\n";
+      std::abort();
+      return false;
+      break;
+    case EEXIST:
+      return true;
+      break;
+    default:
+      return false;
+  }
+}
+
+Path relative(Path const& a, Path const& b)
+{
+  // find common base path
+  auto a_it = a.begin();
+  auto b_it = b.begin();
+  for (; a_it != a.end() && b_it != b.end(); ++a_it, ++b_it) {
+    if (*a_it != *b_it)
+      break;
+  }
+
+  // combine remaining parts of a to result path
+  Path rel(".");
+  for (; a_it != a.end(); ++a_it)
+    rel /= *a_it;
+
+  return rel;
+}
+
+} } // end namespace Dune::Gmsh4
diff --git a/dune/gmsh4/utility/filesystem.hh b/dune/gmsh4/utility/filesystem.hh
index d69a65b51782ad07f78023e209d4bd54563c93f1..ef15a261787d42cd289fbd3ed6530d6a444b8b09 100644
--- a/dune/gmsh4/utility/filesystem.hh
+++ b/dune/gmsh4/utility/filesystem.hh
@@ -9,7 +9,6 @@ namespace Dune
 {
   namespace Gmsh4
   {
-
     // A minimalistic filesystem class
     class Path
         : public std::vector<std::string>
@@ -20,9 +19,9 @@ namespace Dune
 
     public:
 #ifdef _WIN32
-      static constexpr char preferred_separator = '\\';
+      static constexpr char preferredSeparator = '\\';
 #else
-      static constexpr char preferred_separator = '/';
+      static constexpr char preferredSeparator = '/';
 #endif
 
     public:
@@ -49,14 +48,14 @@ namespace Dune
       {}
 
       /// Removes filename path component
-      Path& remove_filename()
+      Path& removeFilename()
       {
         this->pop_back();
         return *this;
       }
 
       /// Returns the path of the parent path
-      Path parent_path() const
+      Path parentPath() const
       {
         return empty() ? Path() : Path(begin(), --end());
       }
@@ -80,17 +79,17 @@ namespace Dune
       /** In Linux, test whether the path starts with `/`, in Windows whether it starts
         * with `[a-z]:\\`.
         **/
-      static bool is_absolute(std::string p);
+      static bool isAbsolute(std::string p);
 
-      bool is_absolute() const { return is_absolute(original); }
+      bool isAbsolute() const { return isAbsolute(original); }
 
-      bool is_relative() const { return !is_absolute(); }
+      bool isRelative() const { return !isAbsolute(); }
 
       /// Check whether path is a regular file
-      bool is_file() const;
+      bool isFile() const;
 
       /// Check whether path is a regular file
-      bool is_directory() const;
+      bool isDirectory() const;
 
       /// Lexicographically compares two paths
       bool operator==(Path const& p)
@@ -123,10 +122,10 @@ namespace Dune
     bool exists(Path const&);
 
     /// Create directory and non existing parent directories.
-    bool create_directories(Path const&);
+    bool createDirectories(Path const&);
 
     /// Returns the current path
-    Path current_path();
+    Path currentPath();
 
     /// Find the path of `a` relative to directory of `b`
     Path relative(Path const& a, Path const& b);