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POArray of extended objects in Fortran
 

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  1. POArray of extended objects in Fortran
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    <p><strong>UPDATE</strong>: Modified the code correcting the mistake, if anyone is interested in it as an example</p> <p>I'm trying to get the hang of OOP in Fortran, but got some problems. Any help will be highly appreciated:</p> <p>I want to store pointers to objects extended by an abstract class in an array and then call one of the abstract subroutines for these objects. However I get an compilation error where I'm trying to call the subroutine:</p> <pre><code>src/Body_set.f90(74): error #6553: A function reference is invoking a subroutine subprogram. [GET_MASS] write(*,*) "Body ", i, " - mass: ", b%get_mass() ----------------------------------------------^ src/Body_set.f90(74): error #6402: prPromoteSym : Illegal KIND &amp; CLASS mix [GET_MASS] write(*,*) "Body ", i, " - mass: ", b%get_mass() ----------------------------------------------^ src/Body_set.f90(74): error #7021: Name invalid in this context [GET_MASS] write(*,*) "Body ", i, " - mass: ", b%get_mass() ----------------------------------------------^ compilation aborted for src/Body_set.f90 (code 1) </code></pre> <p>I've got a abstract class in <strong>Body.f90</strong> with two deferred procedures:</p> <pre><code>module Body_module implicit none private type, public, abstract :: Body private contains procedure(get_mass), deferred :: get_mass procedure(set_mass), deferred :: set_mass end type Body abstract interface function get_mass(self) result(m) import Body class(Body), intent(in) :: self double precision m end function subroutine set_mass(self, m) import Body class(Body) :: self double precision m end subroutine end interface end module Body_module </code></pre> <p>Then I've got a simple class with an pointer array that should keep different objects that extends the abstract <code>Body</code> class, <strong>Body_set.f90</strong> (I've included all used subroutines, but the important one is at the bottom):</p> <pre><code>module Body_set_module use Body_module implicit none private type, public :: Body_container class(Body), pointer :: obj end type Body_container type, public :: Body_set private integer :: num_bodies type(Body_container), allocatable, dimension(:) :: bodies contains procedure :: set_body procedure :: get_body procedure :: get_num_bodies procedure :: print_summary final :: destructor end type Body_set interface Body_set procedure constructor end interface Body_set contains !Object contructor function constructor(num_bodies) result(self) class(body_set),pointer :: self integer :: num_bodies allocate(self) self%num_bodies = num_bodies allocate(self%bodies(num_bodies)) end function constructor !Returns number of bodies stored function get_num_bodies(self) result(num_bodies) class(Body_set), intent(in) :: self integer :: num_bodies num_bodies = self%num_bodies end function get_num_bodies !Set element `i` to point to `new_body` subroutine set_body(self, new_body, i) class(body_set), intent(inout) :: self class(Body), target, intent(in) :: new_body integer, intent(in) :: i self%bodies(i)%obj =&gt; new_body end subroutine set_body !Return pointer to body `i` function get_body(self, i) result(the_body) class(Body_set), intent(in) :: self integer, intent(in) :: i class(Body), pointer :: the_body the_body =&gt; self%bodies(i)%obj end function get_body </code></pre> <p><strong>Important part of Body_set.f90</strong>:</p> <pre><code> !Print a summary of all bodies subroutine print_summary(self) class(body_set), intent(in) :: self integer :: i class(Body), pointer :: b write(*,*) "Summary of ", self%num_bodies, " bodies:" do i=1,self%get_num_bodies() b =&gt; self%get_body(i) write(*,*) "Body ", i, " - mass: ", b%get_mass() end do end subroutine print_summary subroutine destructor(self) type(body_set), intent(in) :: self end subroutine end module Body_set_module </code></pre>
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