ReplaceSubclassWithDelegate.kt

//delegate
class DistanceCalculator() {
    fun calculate(vihecle: Vihecle, time: Float): Float {
        return vihecle.speed * time
    }
}

abstract class Vihecle(open val speed: Float, val model: String) {
    //use the delegate instead of override travel function in each subclass
    val distanceCalculator = DistanceCalculator()
    fun travel(time: Float) {
        println("$model traveled ${distanceCalculator.calculate(this, time)}")
        
    }
    abstract fun drive()
    
}

class Car(override val speed: Float, model: String): Vihecle(speed, model) {
    override fun drive() {
        println("Driving a Car")
    }
}

class Train(override val speed: Float, model: String): Vihecle(speed, model) {
    override fun drive() {
        println("Driving a Train")
    }
}

fun main() {
    val car = Car(60.0f, "Vinfast")
    car.drive()
    car.travel(15f)
}