OCaml Object and Class

class name = object (self) ... end
 
class ['a] stack =
  object (self)
    val mutable list = ([] : 'a list)    (* instance variable *)
    method push x =                      (* push method *)
      list <- x :: list
    method pop =                         (* pop method *)
      let result = List.hd list in
      list <- List.tl list;
      result
    method peek =                        (* peek method *)
      List.hd list
    method size =                        (* size method *)
      List.length list
  end;;
class ['a] stack :
  object
    val mutable list : 'a list
    method peek : 'a
    method pop : 'a
    method push : 'a -> unit
    method size : int
  end

• Virtual Superclass
• Virtual Constructor
• Virtual method