type Controlled is abstract tagged null record
   with Initialize => Initialize,
      Adjust => Adjust,
      Finalize => Finalize,
      Legacy_Heap_Finalization, Exceptions_In_Finalize;

      procedure Initialize (Self : in out Controlled) is abstract;
      procedure Adjust (Self : in out Controlled) is abstract;
      procedure Finalize (Self : in out Controlled) is abstract;

type T is record
   Value : Integer;
   Ref_Count : Natural := 0;
end record;

procedure Inc_Ref (X : in out T);
procedure Dec_Ref (X : in out T);

type T_Access is access all T;

type T_Ref is record
   Value : T_Access;
end record
   with Adjust   => Adjust,
      Finalize => Finalize;

procedure Adjust (Ref : in out T_Ref) is
begin
   Inc_Ref (Ref.Value);
end Adjust;

procedure Finalize (Ref : in out T_Ref) is
begin
   Def_Ref (Ref.Value);
end Finalize;

package P is
   type File (<>) is limited private;

   function Open (Path : String) return File;

   procedure Close (F : in out File);
private
   type File is limited record
      Handle : ...;
   end record
      with Finalize => Close;