(* !!take care!!: this classe have side effect, not a pure oassoc *)
class ['a, 'b] oassoc_buffer :
  int ->
  (< add : 'a * 'b -> 'd; assoc : 'a -> 'b; del : 'a * 'b -> 'd;
   delkey : 'a -> 'd; iter : ('a * 'b -> unit) -> unit; length : int; .. >
     as 'd) ->
object ('o)
  inherit ['a,'b] Oassoc.oassoc

  (* ocollection concrete instantiation of virtual methods *)
  method empty : 'o
  method add : 'a * 'b -> 'o

  method iter : ('a * 'b -> unit) -> unit
  method view : ('a * 'b, 'o) Ocollection.view

  method del : 'a * 'b -> 'o
  method mem : 'a * 'b -> bool
  method null : bool

  (* oassoc concrete instantiation of virtual methods *)
  method assoc : 'a -> 'b
  method delkey : 'a -> 'o

  (* ugly, from objet class, extension trick *)
  method private myflush : unit
  method misc_op_hook2 : unit
end