Factory Method by Scala

Factory method by scala

Vehicle Interface: 
  trait Vehicle {
    def drive
  }
  
Various implement of Vehicle:
  class Car extends Vehicle {
    override def drive {
      println("car comming")
    }
  }
  
  class Bus extends Vehicle {
    override def drive {
      println("bus comming")
    }
  }
  
  class Truck extends Vehicle {
    override def drive {
      println("truck comming")
    }
  }
  
The most important Thing is below:
  object Vehicle {
    def apply(kind: String) = kind match {
      case "car" = new Car()
      case "bus" = new Bus()
      case "truck" = new Truck()
    }
  }
  
The factory is object, scala uses "apply" because we can ignore .apply when call Vehicle. We only use Vehicle("car") to replace Vehicle.apply("car"). This is the beauty of scala.

Test case:
  object Test extends App {
    val myVehicle = Vehicle("car")
    myVehicle drive//car coming
  }