Derived Type Procedures

Type-Bound Procedure

Area Method

A derived type can own procedures that operate on its values. Type-bound calls keep the data and behavior together.

Program

Play the program to choose a rectangle width and call the bound area method.

type_bound_area.f90 
module shape_model
    implicit none
    type :: rectangle
        integer :: width
        integer :: height
    contains
        procedure :: area
    end type rectangle
contains
    function area(self) result(total)
        class(rectangle), intent(in) :: self
        integer :: total
        total = self%width * self%height
    end function area
end module shape_model

program type_bound_area_demo
    use shape_model
    implicit none
    type(rectangle) :: box
    integer :: width
    integer :: total

    width = 
    box = rectangle(width, 5)
    total = box%area()
    print '(I0)', total
end program type_bound_area_demo

module shape_model
    implicit none
    type :: rectangle
        integer :: width
        integer :: height
    contains
        procedure :: area
    end type rectangle
contains
    function area(self) result(total)
        class(rectangle), intent(in) :: self
        integer :: total
        total = self%width * self%height
    end function area
end module shape_model

program type_bound_area_demo
    use shape_model
    implicit none
    type(rectangle) :: box
    integer :: width
    integer :: total

    width = 
    box = rectangle(width, 5)
    total = box%area()
    print '(I0)', total
end program type_bound_area_demo

module shape_model
    implicit none
    type :: rectangle
        integer :: width
        integer :: height
    contains
        procedure :: area
    end type rectangle
contains
    function area(self) result(total)
        class(rectangle), intent(in) :: self
        integer :: total
        total = self%width * self%height
    end function area
end module shape_model

program type_bound_area_demo
    use shape_model
    implicit none
    type(rectangle) :: box
    integer :: width
    integer :: total

    width = 
    box = rectangle(width, 5)
    total = box%area()
    print '(I0)', total
end program type_bound_area_demo
type-bound procedure `procedure :: area` attaches a procedure to the derived type.
class argument `class(rectangle)` receives the object for the method call.
method call `box%area()` calls the procedure through the value.