db::Subitems< Tag, typename > Struct Template Reference

Struct that can be specialized to allow DataBox items to have subitems. Specializations must define: More...

#include <Subitems.hpp>

Public Types
using	type = tmpl::list<>

Detailed Description

template<typename Tag, typename = std::nullptr_t>
struct db::Subitems< Tag, typename >

Struct that can be specialized to allow DataBox items to have subitems. Specializations must define:

• using type = tmpl::list<...> listing the subtags of Tag
• A static member function to initialize a subitem of a simple item:

  template <typename Subtag>
  static void create_item(
      const gsl::not_null<typename Tag::type*> parent_value,
      const gsl::not_null<typename Subtag::type*> sub_value) noexcept;

  Mutating the subitems must also modify the main item.
• A static member function evaluating a subitem of a compute item:

  template <typename Subtag>
  static typename Subtag::type create_compute_item(
      typename Tag::type& parent_value) noexcept;