payments.scala

object Payments {
  
  trait PaymentProcessorType {
  }
  
  object DefaultPaymentProcessorType extends PaymentProcessorType

  trait PaymentProcessor {
    def processorType: PaymentProcessorType
    def process(payment: Payment): Unit
  }
  
  class DefaultPaymentProcessor extends PaymentProcessor {
    def processorType: PaymentProcessorType = DefaultPaymentProcessorType
    def process(payment: Payment): Unit = ???
  }
  
  case class Payment(paymentProcessorType: PaymentProcessorType)
  
  def processPayment(p: Payment): Unit = {
    val processor = p.paymentProcessorType match {
      case DefaultPaymentProcessorType => new DefaultPaymentProcessor
    }
    assert(processor.processorType == p.paymentProcessorType)
    processor.process(p)
  }
}