program main
  implicit none

  type my_type
     integer, pointer :: my_size(:) 
     !integer, allocatable :: my_size(:)  ! F03 allows the use of allocatables inside derived data types
  end type my_type

  ! However do remember that:
  ! (1) Pointers start life undefined where as allocatables start life as unallocated
  ! (2) Pointers will leak memory if not explicitly deallocated. In particular deallocating 
  !     a derived type will NOT deallocate any pointer components. Allocatable components
  !     automatically deallocate when out of scope
  ! (3) When you copy (i.e. assign) a derived type value that has a pointer component, you
  !     end up with a second pointer to the same memory. You don't end up with two copies 
  !     of the data

  type(my_type), allocatable :: x(:)

  allocate(x(3))

  allocate(x(1)%my_size(3))
  allocate(x(2)%my_size(2))
  allocate(x(3)%my_size(1))

  print*, x(1)%my_size
  print*, x(2)%my_size
  print*, x(3)%my_size

  deallocate(x(3)%my_size, x(2)%my_size, x(1)%my_size) 
  deallocate(x)
  
end program main