jdv_article19 (macros example)

gistfile1.scala

object Log 
{
  

  def apply(msg: String): Unit = macro applyImpl

  def applyImpl(c: Context)(msg: c.Expr[String]):c.Expr[Unit] =
  {
   import c.universe._
   val tree = q"""if (Log.enabled) {
                      Log.log(${msg})
                  }
               """
   c.Expr[Unit](tree)
  }

}