unary

• unary_ 를 쓴 다음 꼭 한칸 띄고 : 을 써야 한다.
• 총 4개의 문자만 된다. +, - ,! , ~

class MyString(str:String){
  def unary_- = new MyString(new StringBuilder(str).reverse.toString)
  def unary_+ = new MyString(new StringBuilder(str).reverse.toString)
  def unary_! = new MyString(new StringBuilder(str).reverse.toString)
  def unary_~ = new MyString(new StringBuilder(str).reverse.toString)

  override def toString = str
}

val myString = new MyString("abcd")

println(myString)     // prints "abcd"
println(-myString)    // prints "dcba"

ref : https://gist.github.com/p3t0r/54679