一天一段scala代码（十一）

package examples




class Fraction(n:Int,d:Int)
{
  private val num =n
  private val den=d
  def *(other:Fraction) = new Fraction(num*other.num,den*other.den)
  //重载称号操作符
}


object Fraction
{
  def apply(n:Int,d:Int)  = new Fraction(n,d)
  def unapply(input:Fraction)=
  {
    if(input.den==0) None
    else Some((input.num,input.den))
  }
}





object Example11 extends App{
 //元组提取器
  val Fraction(a,b) = Fraction(1,2)*Fraction(1,3)
  println(a,b)
  
  
  
  //额外, 单个参数或者无参数的需要用option;提取任意长度的需要用unapplaySeq
  
  
  
}