Templating

• Templating and polymorphism are arguably the most powerful features of C++, but with great power comes great potential pain.
  • EAMxx makes extensive use of templates, throughout, and this is encouraged but should be done judiciously.
  • Adding complexity should only be done in service of improved functionality or speed because these typically come at the price of clarity and readability.
• Template parameters should mostly obey the same naming conventions of the type they correspond to.
  • lower_snake_case for variables.
    • E.g., variables of integral types or objects.
  • UpperCamelCase for types, classes, or structs.

  • However, terseness that follows EAMxx or Kokkos conventions can improve readability, though favoring descriptiveness should be the default case.

    • Take this update() function declaration as an example.

      template<int *atom_counter, HostOrDevice HD = Device, typename ST>
      void update(const Field &x, const ST alpha, const ST beta);
      

    • The first template parameter is an integer-pointer that self-describes.

    • The second template parameter, HD (enum type), is tersely-named but the type provides sufficient descriptive information.
    • The second and third template parameters, including ST ("scalar type"), are standard conventions used throughout EAMxx, and the abbreviation saves an enormous amount of space in aggregate.