module Rectangle_mod
  use kinds_mod, only : DP
  use Shape_mod, only : Shape
  implicit none
  private

  type, extends(Shape), public :: Rectangle
     private
     real(DP) :: length
     real(DP) :: width
   contains
     private
     procedure, pass(this) :: ConstructRectangle
     procedure, pass(this), public :: getArea
     generic, public :: Construct => ConstructRectangle
  end type Rectangle

contains

  subroutine ConstructRectangle(this, length, width, xCenter, yCenter)
    class(Rectangle), intent(inout) :: this
    real(DP), intent(in) :: length
    real(DP), intent(in) :: width
    real(DP), intent(in) :: xCenter
    real(DP), intent(in) :: yCenter

    !.. Create the base class
    call this%Construct(xCenter=xCenter, yCenter=yCenter)

    print *, "Constructing rectangle"

    this%length = length
    this%width = width
    !How to invoke the base class constructor here?
    !The line below works for non-abstract base classes where the
    !constructor result can be type(Shape)
  end subroutine ConstructRectangle

  function getArea(this) result(area)
    class(Rectangle), intent(in) :: this
    real(DP) :: area
    area = this%length * this%width
  end function getArea
end module Rectangle_mod