class interface DRAWABLE_RECTANGLE
creation
   make
      --  Create object.
feature(s) from DRAWABLE_RECTANGLE
   --  Position
   set_position (rect: RECTANGLE)
      --  Set rectangle to be drawn.
      require
         valid_rectangle: rect /= Void
      ensure
         done: position.is_equal(rect)
invariant
   valid_position: position /= Void;
end of DRAWABLE_RECTANGLE