第一次真正自己写scala. 纪念下

scala写的分数类, 支持+-*/约分, 当左操作数约分设为true, 所有结果约分设为true, 可惜还是用了var

// 2012/5/15

// let it go

看了一个Java写的功能完全一样的分数类, 80+行, 不包括注释和空白行, scala39行搞定了

*******************************************************************************************************

扩充分数类, 实现前置一元操作符取负-, 取倒数~, 实现不等号比较, 实现跨类型计算(implicit conversion)

// 2012/5/16object Rational {  implicit def toRational(a: Any) = {    var d = a.toString.toDouble    var numer = d    var denom = 1    while (numer != numer.ceil) {      numer *= 10      denom *= 10    }    new Rational(numer.toInt, denom.toInt).--  }}class Rational(x: Int, y: Int){  require(y != 0)    val numer = x  val denom = y  private val cd = gcd(numer abs, denom abs)  private var autoreduce = false    def getAutoreduce = autoreduce    def setAutoreduce(bool: Boolean) = autoreduce = bool    def -- : Rational = new Rational(numer / cd, denom / cd)    private def fuc(x: Int, y: Int): Rational = {    var ra = new Rational(x, y)    if (autoreduce) {      ra = ra.--      ra.setAutoreduce(true)    }    ra  }     def +(b: Rational) = fuc(numer * b.denom + denom * b.numer, denom * b.denom)    def -(b: Rational) = fuc(numer * b.denom - denom * b.numer, denom * b.denom)    def *(b: Rational) = fuc(numer * b.numer, denom * b.denom)    def /(b: Rational) = {    require(b != 0)    fuc(numer * b.denom, denom * b.numer)  }    def unary_+ = this    def unary_- = {    val ra = new Rational(-numer, denom)    if (autoreduce) ra.setAutoreduce(true)    ra  }    def unary_~ = {    require(numer != 0)    val ra = new Rational(denom, numer)    if (autoreduce) ra.setAutoreduce(true)    ra  }    override def equals(b: Any): Boolean = b match{    case b: Rational => {      val c = this.--      val d = b.--      c.toDouble * d.toDouble >= 0 && c.numer.abs == d.numer.abs && c.denom.abs == d.denom.abs    }    case _ => this.toDouble == b  }    def >=(b: Rational) = (this - b) isPositive    def <=(b: Rational) = !(this >= b) || this == b    def >(b: Rational) = !(this <= b)    def <(b: Rational) = !(this >= b)    private def isPositive = numer * denom >= 0    override def toString(): String = {    if (this.toDouble < 0) {      "-" + numer.abs + "/" + denom.abs    }else "" + numer.abs + "/" + denom.abs  }    def toDouble : Double = numer.toDouble / denom.toDouble    private def gcd(x: Int, y: Int): Int = if (y == 0) x else gcd(y, x % y)}