First presented at CALECO
Previous: Systems as objects

Timeless objects

Both examples so far have involved objects which change with time. MM can also be used for objects where time is irrelevant. An example would be where one needs to calculate the cost of painting a set of rooms, estimating each room's needs from the surface area of its walls:

object room {
  < area:real length:real width:real height:real >
  area = 2*length*height +
         2*width*height
}

object bathroom {
  inherits( room )
  length = 10 & width = 12 & height = 14
}

object bedroom {
  inherits( room )
  length = 12 & width = 16 & height = 14
}

object house {
  inherits( bathroom + bedroom )
  < paint_unit_cost:real total_cost:real >
  paint_unit_cost = 326
  total_cost = (bathroom.area + bedroom.area) * paint_unit_cost
}