Howdy, What would be the idiomatic Kotlin way to ...

# getting-started

[Conor Fennell]

Howdy,

What would be the idiomatic Kotlin way to go here?

data class Calculation(
    val money: Double,
    val multiplier: Double,
)
fun Calculation.total(): Double = money * multiplier

OR

data class Calculation(
    val money: Double,
    val multiplier: Double,
) {
    fun total(): Double = money * multiplier
}

[wbertan]

I would do like this:

data class Calculation(
        val money: Double,
        val multiplier: Double,
    ) {
        val total: Double
            get() = money * multiplier
    }

[wbertan]

But about the question of making extension or not. I would see, if I would use it everywhere Calculation is required, I would put inside Calculation . If it would be in only one specific module, I would make an Extension with visibility only in that module.

[elizarov]

I would look at whether the total is conceptually a part of Caculation or just an utility. See https://elizarov.medium.com/extension-oriented-design-13f4f27deaee