Dependency Injection

DependencyInjection.scala

trait Service {
  def sendMessage(msg: String, recv: String): Unit
}
class SMSService extends Service {
  def sendMessage(msg: String, recv: String) =
    println(s"SMS sent to ${recv} containing ${msg}")
}
class EmailService extends Service {
  def sendMessage(msg: String, recv: String) =
    println(s"Email sent to ${recv} containing ${msg}")
}

trait Consumer {
  def processMessage(msg: String, recv: String): Unit
}
class Application(private val service:Service) extends Consumer {
  def processMessage(msg: String, recv: String): Unit =
    service.sendMessage(msg, recv)
}

trait Injector {
  def getConsumer: Consumer
}
class SMSInjector extends Injector {
  def getConsumer: Consumer =
    new Application(new SMSService)
}
class EmailInjector extends Injector {
  def getConsumer: Consumer =
    new Application(new EmailService)
}

object Main extends App {
  val injector: Injector = new EmailInjector()
  val consumer: Consumer = injector getConsumer
  consumer.processMessage("Hello", "To you")
}