diff --git a/src/hdf5_array.hpp b/src/hdf5_array.hpp
index 455d4b7..fc1a727 100644
--- a/src/hdf5_array.hpp
+++ b/src/hdf5_array.hpp
@@ -44,6 +44,9 @@ knowledge of the CeCILL license and that you accept its terms.
 #include <boost/multi_array.hpp>
 #include <boost/type_traits/is_same.hpp> 
 #include <boost/type_traits/is_floating_point.hpp> 
+#include <boost/preprocessor/cat.hpp>
+#include <boost/preprocessor/stringize.hpp>
+#include <boost/preprocessor/seq/for_each.hpp>
 #include <vector>
 #include <H5Cpp.h>
 
@@ -59,7 +62,7 @@ namespace CosmoTool {
 
   template<typename T, class Enable = void> struct get_hdf5_data_type
   {
-    static H5::PredType type()  
+    static H5::DataType type()  
       {   
           BOOST_MPL_ASSERT_MSG(0, Unknown_HDF5_data_type, ()); 
           return H5::PredType::NATIVE_DOUBLE; 
@@ -68,7 +71,7 @@ namespace CosmoTool {
   
   #define HDF5_TYPE(tl, thdf5) \
   template<typename T> struct get_hdf5_data_type<T, typename boost::enable_if<boost::is_same<T, tl> >::type>  \
-    { static H5::PredType type() { return H5::PredType::thdf5; }; }
+    { static H5::DataType type() { return H5::PredType::thdf5; }; }
   
   HDF5_TYPE(char              , NATIVE_CHAR);
   HDF5_TYPE(long long         , NATIVE_LLONG);
@@ -202,6 +205,39 @@ namespace CosmoTool {
       hdf5_read_array(fg, data_set_name, data, hdf5_ComplexType<T>::ctype()->type);
   }
 
+
+#define CTOOL_HDF5_NAME(STRUCT) BOOST_PP_CAT(hdf5_,STRUCT)
+#define CTOOL_HDF5_INSERT_ELEMENT(r, STRUCT, element) \
+     { \
+       CosmoTool::get_hdf5_data_type<BOOST_PP_TUPLE_ELEM(2, 0, element)> t; \
+       position = offsetof(STRUCT, BOOST_PP_TUPLE_ELEM(2, 1, element)); \
+       type.insertMember(BOOST_PP_STRINGIZE(BOOST_PP_TUPLE_ELEM(2, 1, element)),  position, t.type()); \
+     } 
+  
+#define CTOOL_STRUCT_TYPE(STRUCT, TNAME, ATTRIBUTES) \
+namespace CosmoTool { \
+    class CTOOL_HDF5_NAME(STRUCT) {  \
+    public:  \
+      H5::CompType type;  \
+  \
+      CTOOL_HDF5_NAME(STRUCT)() : type(sizeof(STRUCT)) \
+      {  \
+        long position; \
+        BOOST_PP_SEQ_FOR_EACH(CTOOL_HDF5_INSERT_ELEMENT, STRUCT, ATTRIBUTES) \
+        type.pack(); \
+      }  \
+      \
+      static const CTOOL_HDF5_NAME(STRUCT) *ctype() \
+      { \
+        static CTOOL_HDF5_NAME(STRUCT) singleton; \
+        return &singleton; \
+      } \
+    }; \
+    template<> struct get_hdf5_data_type<STRUCT> { \
+        static H5::DataType type() { return CTOOL_HDF5_NAME(STRUCT)::ctype()->type; }; \
+    }; \
+};
+
 };
 
 #endif