(***********************************************************************)
(*                                                                     *)
(*            cast objet en O'Caml                                     *)
(*                                                                     *)
(*            Emmanuel Chailloux, Equipe PPS, universite P7            *)
(*                                                                     *)
(*                                                                     *)
(***********************************************************************)

(* $Id: test3.ml,v 1.2 2001/08/30 15:40:37 emmanuel Exp $ *)

(* test3.ml : fichier de test 

            t
          / | \
        /   |   \
       a    b    c
        \   |   /
         \  |  /
           abc

 *)

class t = 
  object
  end;;

class a (x:int) = 
  object
    inherit t
    val a = x
    method get_a = a
  end;;

class b (x:int) = 
  object
    inherit t
    val b = x
    method get_b = b
  end;;

class c (x:int) = 
  object
    inherit t
    val c = x
    method get_c = c
  end;;

class abc x = 
  object(self)
    inherit a x
    inherit b x
    inherit c x
    method get_abc = (self#get_a), (self#get_b), (self#get_c)
  end;;

let abc1 = new abc 1;;
let a1 =  (upcast abc1 from abc to  a);;
let b1 =  (upcast abc1 from abc to  b);;
let c1 =  (upcast abc1 from abc to  c);;

downcast a1 from a to abc;;
downcast b1 from b to abc;;
downcast c1 from c to abc;;

let t1 = (upcast a1 from a to  t);;
let t2 = (upcast b1 from b to  t);;
let t3 = (upcast c1 from c to  t);;

downcast t1 from t to a;;
downcast t1 from t to b;;
downcast t1 from t to c;;
let r = downcast t1 from t to abc;;
r#get_abc;;
print_string "OK";;
print_newline();;

try 
  ignore (upcast(downcast b1 from b to abc) from abc to c); "OK"
with _ -> "PB";;