logger with value

gistfile1.scala

def myFunc() = {
  val rs = calcSomeResult()
  logger.info("result is:" + rs)
  rs
}
为避免上面的麻烦写法:

object LogUtil {
  def kestrel[A](x: A)(f: A => Unit): A = { f(x); x }
  def logV[A](f: String => Unit)(s: String, x: A) = kestrel(x) { y => f(s + ": " + y) }
}

----------------------------
class LogUtilSpec extends FlatSpec with ShouldMatchers {
  val logger = LoggerFactory.getLogger(this.getClass())
  import LogUtil._

  "LogUtil" should "print log info and keep the value, and the calc for value should only be called once" in {
    def calcValue = { println("calcValue"); 100 } // to confirm it's called only once 
    val v = logV(logger.info)("result is", calcValue)
    v should be === 100
  }
}