try suggested number_of_componentns alternative

bfps/cpp/field.hpp

@@ -58,6 +58,7 @@ class field
     private:
         rnumber *__restrict__ data; /**< data array */
     public:
+        static const int number_of_components = ncomp(fc);
         hsize_t npoints; /**< total number of grid points. Useful for normalization. */
         bool real_space_representation; /**< `true` if field is in real space representation. */
 

bfps/cpp/particles/particles_field_computer.hpp

@@ -12,16 +12,6 @@ template <class partsize_t,
           class interpolator_class,
           int interp_neighbours>
 class particles_field_computer {
-    // TODO but not critical, add in field:
-    // static const int nb_components = ncomp(fc);
-    // and use it as field_class::nb_components
-    // but failed up to now....
-    template <typename rnumber,
-              field_backend be,
-              field_components fc>
-    static constexpr int nbcomp(const field<rnumber, be, fc>& /*field*/){
-        return ncomp(fc);
-    }
 
     const std::array<int,3> field_grid_dim;
     const std::pair<int,int> current_partition_interval;
@@ -77,7 +67,7 @@ public:
                                    const real_number particles_positions[],
                                    real_number particles_current_rhs[],
                                    const partsize_t nb_particles) const {
-        constexpr int nb_components_in_field = nbcomp(field);
+        constexpr int nb_components_in_field = field.number_of_components;
         static_assert(nb_components_in_field <= size_particle_rhs, "Cannot store all the component in the given array");
         TIMEZONE("particles_field_computer::apply_computation");