How can I take any function as input for my Scala wrapper method?

Question

Let\'s say I want to make a little wrapper along the lines of:

def wrapper(f: (Any) => Any): Any = {
  println(\"Executing now\")
  val res = f
  println(\"Ex         


        

Answer 1

If you want your wrapper method to execute the wrapped method inside itself, you should change the parameter to be 'by name'. This uses the syntax => ResultType.

def wrapper(f: => Any): Any = {
  println("Executing now")
  val res = f
  println("Execution finished")
  res
}

You can now do this,

wrapper {
  println("2")
}

and it will print

Executing now
2
Execution finished

If you want to be able to use the return type of the wrapped function, you can make your method generic:

def wrapper[T](f: => T): T = {
  println("Executing now")
  val res: T = f
  println("Execution finished")
  res
}