Fortran: parameterized derived types in a 'select type' clause

Question

I am trying to use parameterized derived types in a subroutine using an unlimited polymorphic pointer.

Is is possible to use a 'select type' clause for parameterized types?

I've tried something along the following lines but am getting a compilation error. (Syntax error at or near TYPE)

module mod_real
  implicit none

  type :: type1(k)
    integer, kind :: k = 4
    real(kind=k) :: val
  end type type1

  contains

    subroutine out(in)
      class(*) :: in
      select type(in)
        type is (type1(4))
          print *, 'real(4):', in%val
        type is (type1(8))
          print *, 'real(8):', in%val
      end select
    end subroutine out

end module mod_real 

program real_test
  use mod_real

  type(type1(4)) :: p
  type(type1(8)) :: p2 

  p%val = 3.14
  p2%val = 3.1456d0

  call out(p)
  call out(p2)       

end program real_test 

the lines with "type is (type1(4))" and "type is (type1(8))" are indicated as having incorrect syntax. I am using the Portland Group Fortran compiler (version 13.5-0).

Auklet

looks OK, which version of PGI Fortran are you using? – Congeal

I'm using version 13.5-0 – Auklet

Note, most compilers did not implement parametrized derived types completely yet. Maybe also your compiler has only partial support for it. – Gulfweed

Answer 1

At the time of the question's writing, the issue was most probably compiler support, check this page:

• http://fortranwiki.org/fortran/show/Fortran+2003+status

As to the actual question, in this case you could use a compile-time solution with module procedure, which wouldn't need polymorphism and thus might have less overhead:

module mod_real

type type1(k)
  ... ! as before
end type

interface out
  module procedure out4, out8
end interface

contains

 subroutine out_type4(x)
   type(type1(4)), intent(in) :: x
   print*, 'real(4):' x%val   
 end subroutine

 subroutine out_type8(x)
   type(type1(8)), intent(in) :: x
   print*, 'real(8):' x%val   
 end subroutine

end module
program 
  ... ! as before
end program

Tigress

At the time of writing the question PGI already claimed FULL Fortran 2003 compliance. You did not answer whether it is possible to use parametrized derived types in select type – Simplify