Add a trait for h5_compound

c++/h5/macros.hpp

@@ -30,14 +30,6 @@
 #define H5_AS_STRING(...) H5_AS_STRING2(__VA_ARGS__)
 #define H5_AS_STRING2(...) #__VA_ARGS__
 
-// ---------------- Requires ----------------
-
-#ifdef __clang__
-#define H5_REQUIRES(...) __attribute__((enable_if(__VA_ARGS__, H5_AS_STRING2(__VA_ARGS__))))
-#elif __GNUC__
-#define H5_REQUIRES(...) requires(__VA_ARGS__)
-#endif
-
 // ---------------- Print ----------------
 
 #define H5_PRINT(X) std::cerr << H5_AS_STRING(X) << " = " << X << "      at " << __FILE__ << ":" << __LINE__ << '\n'

c++/h5/object.hpp

@@ -138,6 +138,8 @@ namespace h5 {
    * @{
    */
 
+  template <typename T>
+  constexpr bool is_h5_compound = false;
   namespace detail {
 
     // Map a C++ type to an HDF5 type (specializations are in object.cpp).

c++/h5/scalar.hpp

@@ -67,7 +67,8 @@ namespace h5 {
    * @param x Scalar value to be written.
    */
   template <typename T>
-  void h5_write(group g, std::string const &name, T const &x) H5_REQUIRES(std::is_arithmetic_v<T> or is_complex_v<T> or std::is_same_v<T, dcplx_t>) {
+    requires(std::is_arithmetic_v<T> or is_complex_v<T> or std::is_same_v<T, dcplx_t> or is_h5_compound<T>)
+  void h5_write(group g, std::string const &name, T const &x) {
     array_interface::write(g, name, array_interface::array_view_from_scalar(x), false);
   }
 
@@ -82,7 +83,8 @@ namespace h5 {
    * @param x Scalar variable to be read into.
    */
   template <typename T>
-  void h5_read(group g, std::string const &name, T &x) H5_REQUIRES(std::is_arithmetic_v<T> or is_complex_v<T> or std::is_same_v<T, dcplx_t>) {
+    requires(std::is_arithmetic_v<T> or is_complex_v<T> or std::is_same_v<T, dcplx_t> or is_h5_compound<T>)
+  void h5_read(group g, std::string const &name, T &x) {
     // backward compatibility to read complex values stored the old way (in a subgroup)
     if constexpr (is_complex_v<T>) {
       if (g.has_subgroup(name)) {
@@ -122,7 +124,8 @@ namespace h5 {
    * @param x Scalar value to be written.
    */
   template <typename T>
-  void h5_write_attribute(object obj, std::string const &name, T const &x) H5_REQUIRES(std::is_arithmetic_v<T> or is_complex_v<T>) {
+    requires(std::is_arithmetic_v<T> or is_complex_v<T> or is_h5_compound<T>)
+  void h5_write_attribute(object obj, std::string const &name, T const &x) {
     array_interface::write_attribute(obj, name, array_interface::array_view_from_scalar(x));
   }
 
@@ -137,7 +140,8 @@ namespace h5 {
    * @param x Scalar variable to be read into.
    */
   template <typename T>
-  void h5_read_attribute(object obj, std::string const &name, T &x) H5_REQUIRES(std::is_arithmetic_v<T> or is_complex_v<T>) {
+    requires(std::is_arithmetic_v<T> or is_complex_v<T> or is_h5_compound<T>)
+  void h5_read_attribute(object obj, std::string const &name, T &x) {
     array_interface::read_attribute(obj, name, array_interface::array_view_from_scalar(x));
   }