7中置一元赋值结合apply和updateunapply提取器 _赋值

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中置操作符

scala> 1 to 5 res0: scala.collection.immutable.Range.Inclusive = Range(1, 2, 3, 4, 5)scala> 1 -> 2 res1: (Int, Int) = (1,2)scala> 1 until 5 res2: scala.collection.immutable.Range = Range(1, 2, 3, 4)

一元操作符

scala> ~1 res3: Int = -2scala> -1 res4: Int = -1scala> +1 res5: Int = 1scala> 1.unary_~ res6: Int = -2scala> 1.unary_- res7: Int = -1scala> 1.unary_+ res8: Int = 1

赋值操作符
结合性：以：结尾的操作符，都是右操作符

scala> 4 +: arr res23: Array[Int] = Array(4, 1, 2, 3)scala> arr.+:(4) res24: Array[Int] = Array(4, 1, 2, 3)scala> arr :+ 4 res25: Array[Int] = Array(1, 2, 3, 4)scala> arr.:+(4) res28: Array[Int] = Array(1, 2, 3, 4)

scala> 1::2::3::Nil res29: List[Int] = List(1, 2, 3)

apply和update
可自定义apply和update方法
f(arg1,arg2,arg3)　等同于 f.apply(arg1,arg2,arg3)定义在伴生对象中
如果出现在赋值语句左侧：f(arg1,arg2,arg3) = value，则等同于 f.update(arg1,arg2,arg3,value)定义在类中

【7中置一元赋值结合apply和updateunapply提取器】unapply
Option 可空：None空和Some有值
Fac(a,b) = f

class ApplyDemo(var a:Int,var b:Int) {def update(ab:(Int,Int)): Unit ={ this.a = ab._1 this.b = ab._2 } }object ApplyDemo { def apply(a: Int, b: Int): ApplyDemo = new ApplyDemo(a, b)def unapply(arg: ApplyDemo): Option[(Int, Int)] ={ if(arg.b == 0)None else Some((arg.a,arg.b)) }def main(args: Array[String]): Unit = { //apply的使用 val v1 = new ApplyDemo(1,2) val v2 = ApplyDemo(3,4)println(v1.a," ",v1.b) println(v2.a," ",v2.b)//update的使用 v2.update((5,6)) v2()=(7,8)//unapply的使用 val ApplyDemo(a,b) = v2 println(a," ",b)} }