import kotlin.reflect.KProperty

data class User(val id: Int, val name: String)

class PropertyTransfer {
    var _user: User? = null
    var user: User? by object {
        operator fun getValue(thisRef: PropertyTransfer, property: KProperty<*>): User? {
            println("${property.name}がgetされました")
            return _user
        }

        operator fun setValue(thisRef: PropertyTransfer, property: KProperty<*>, userValue: User?) {
            _user = userValue
            println("${property.name}に${userValue}がsetされました")
            println("${_user?.id}")
            println("${_user?.name}")
        }
    }
}

fun main(args: Array<String>) {
    val propertyTransfer = PropertyTransfer()
    println(propertyTransfer.user)
    val userSetup = User(1, "太郎")
    propertyTransfer.user = userSetup
    println(propertyTransfer.user)
}