Fortran features to take advantage of

[ekluzek]

I learned about this in some of the conferences I've been to (US-RSE, SEA ISS) as well as working with John D. in CISL. There are a lot of useful Fortran features that we should start taking advantage of, that will help us get better, more robust code for CTSM.

For example here are some keywords to start using more:

For functions and subroutines:

• pure
• simple
• elemental
• final
• finalize

Data in OO types:

• non_overridable – data that can’t be changed in extensions

[ekluzek]

Here's an example of using finalize from John Dennis. This is where the compiler will remember to call the final method for you, which can make deallocating memory happen automatically.

type :: Coords1D
…
   procedure :: finalize                ! User-callable
   final     :: finalize_Coords1D   ! Auto-finalize
end type Coords1D
subroutine finalize(this)
  class(Coords1D), intent(inout) :: this
  call finalize_Coords1D(this)
end subroutine finalize
! Deallocate and reset to initial state.
subroutine finalize_Coords1D(this)
  type(Coords1D) :: this
  this%n = 0; this%d = 0
…
  if(allocated(this%rdst)) deallocate(this%rdst)
end subroutine finalize_Coords1D