An InformLanguage demonstration object, representing a Door

 Object -> StoneDoor "stone door"
  with description "It's just a big stone door.",
       name "door" "massive" "big" "stone" "yellow",
       when_closed
           "The passage is barred by a massive door of yellow stone.",
       when_open
           "The great yellow stone door is open.",
       door_to
       [;  if (location==Corridor) return Shrine; return Corridor; ],
       door_dir
       [;  if (location==Shrine) return n_to; return s_to; ],
       with_key stone_key,
       found_in  Corridor  Shrine,
  has  static door openable lockable locked;