factory-function-approach-2.kt

class PhoneNumberScreen(
    private val phoneNumber: PhoneNumber
) {

    fun render() {
        if (phoneNumber.value.isNotEmpty()) {
            println("Phone number: ${phoneNumber.value}")
        } else {
            println("Invalid phone number")
        }
    }
}

fun main() {
    val contact = Contact(PhoneNumber("12345"))
    show(contact.phoneNumber) // "Phone number: 12345"

    val contactWithInvalidPhoneNumber = Contact(PhoneNumber(""))
    show(contactWithInvalidPhoneNumber.phoneNumber) // "Invalid phone number"
}

private fun show(phoneNumber: PhoneNumber) {
    val phoneNumberScreen = PhoneNumberScreen(phoneNumber)
    phoneNumberScreen.render()
}