effectful.scala

package com.banksimple.util

private[util] final class Effectful[T](val origin: T) {
  /**
   * A special case of doto, andAlso is useful for
   * quick logging or output tasks. Similar in use
   * to doto, but only takes one function.
   * */
  def andAlso(x: T => Unit): T = { x(origin) ; origin }

  /**
   * Useful if you want to cause side effects
   * upon the completion of a value, but then
   * return the value. This frequently occurs
   * in server-oriented code where logging and
   * metrics events need to be created.
   * */
  def andThen(x: => Unit): T = { x ; origin }

  /**
   * Copying Clojure's (doto JavaObject ...)
   *
   * Takes an object and causes side effects on it, then
   * returns the object. Useful with old-style mutable
   * java objects that require lots of setters to be
   * called in sequence. Calls can be nested.
   *
   * Example usage:
   * {{{
   * (new Id).doto(
   *   _.setType(Id.SSN),
   *   _.setValue("123-456-7890")) 
   * }}}
   */
  def doto(mutators: Function1[T,Unit]*): T = {
    for( f <- mutators ) { f(origin) }
    origin
  }
}

trait EffectfulImplicits {
  implicit def any2Effectful[T](x: T): Effectful[T] = new Effectful(x)
}

object Effectful extends EffectfulImplicits