I am trying to pass a function as an argument to another function. When I try using a simple function it works fine. But when I try to pass a function belonging to an object I get an error. Here's a simple code to recreate the problem in Fortran.
module classb
use iso_c_binding
implicit none
type :: fr
integer(c_int) :: order
contains
procedure, pass :: get_val
procedure, nopass :: fn
end type fr
contains
subroutine get_val(this)
class(fr), intent(inout) :: this
write(*, *) this%order
end subroutine get_val
function fn(a) result(b)
integer(c_int), intent(in) :: a
integer(c_int) :: b
b = 2*a
end function fn
end module classb
module callb
use iso_c_binding
use classb
implicit none
interface
function func(a) result(b)
use iso_c_binding
implicit none
integer(c_int), intent(in) :: a
integer(c_int) :: b
end function func
end interface
contains
subroutine do_call_b(f, a)
procedure(fn) :: f
integer(c_int) :: a
write(*, *) f(a)
end subroutine do_call_b
subroutine get_value()
type(fr) :: f
f = fr(order = 1)
call f%get_val()
call do_call_b(f%fn, 1)
end subroutine get_value
end module callb
program main
use callb
call get_value()
end program main
I get the error
call do_call_b(f%fn, 1)
1
Error: Expected argument list at (1)
Is callbacks using objects not supported in Fortran. If so how could I do something like this.
