Simple way to implement a group of queues in Fortran?

Question

Suppose that I need to implement at least 5 queues in one procedure, each of it from a different defined type. How can achive this in a simple and short way?.

Anot

Answer 1

I have implemented the fortran template in Ruby, which is integrated in my CodeMate. The template syntax is similar to C++. I have implemented double linked list. The template definition snippets are as following:

...

template:list_t <type elem_t>
type list_t
    integer :: num_elem = 0
    type(elem_t), pointer :: head, tail
contains
    ...
    procedure :: insert => list_insert
    ...
end type list

...

template:list_insert@list_t <type elem_t>
subroutine list_insert(this, elem, ...)

    class(list_t), intent(inout) :: this
    type(elem_t), intent(out), pointer :: elem

    ...

end subroutine list_insert

And the template instance is as following:

type(list_t<foo_t>) foo_list

where foo_t is a user-defined type that extends list_elem_t<foo_t>. The you can insert element into foo_list by

call foo_list%insert(elem, ...)

I think my solution to Fortran template is natural.

Answer 2

Have you considered unlimited polymorphic pointers? See, for ex., pp 269 ff in "Modern Fortran Explained".

Answer 3

If you really want templates, there is Pyf95++. It brings templating and an STL for Fortran using a preprocessor. (for download here)

A generic linked-list that uses transfer() can be found in FLIBS.

(Otherwise with a bleeding edge compiler you can use unlimited polymorphism as suggested by Richard Lozes.)