class DefinedOr[T] {
	var	_v:Option[T] = None
	def this(n:T) = { this(); this.v = n }
	def v:Option[T] = _v
	def v_=(v:T) = { _v = Some(v) }
	def ||=(n:T) = { v = v match { case None => n; case Some(x) => x } }
}
object Main {
	def main(args:Array[String]) = {
		var	d:DefinedOr[Int] = new DefinedOr
		println(d.v)
		d ||= 0
		println(d.v)
		d ||= 1
		println(d.v)
		d = new DefinedOr(2)
		println(d.v)
		d ||= 0
		println(d.v)
	}
}