Another question about constructor usage in data classes, is something like this possible without cy...

# getting-started

[Jukka Siivonen]

Another question about constructor usage in data classes, is something like this possible without cycle error?

[Jukka Siivonen]

data class ReasonItem private constructor(
    val reason: Reason,
    val notes: String?
) {
    constructor(
        reason: FooReason
    ) : this(reason, null)

    constructor(
        reason: BarReason,
        notes: String
    ) : this(reason, notes)
}

[Jukka Siivonen]

of course I could create separate *Item types too but..

[Jukka Siivonen]

maybe two subtypes makes more sense because getter is still nullable in both cases

[Joffrey]

Use reason as Reason when you want to call the private constructor from the others.

That said, it might be more interesting to use a sealed class which does or does not have the notes property depending on the type

[Joffrey]

sealed class ReasonItem(open val reason: Reason)

data class FooReasonItem(
    override val reason: FooReason,
) : ReasonItem(reason)

data class BarReasonItem(
    override val reason: BarReason,
    val notes: String,
) : ReasonItem(reason)

[Jukka Siivonen]

Yeah, also thanks for the "reason as Reason" tip

[Joffrey]

Overloads are resolved statically at compile time based on the declared type of the variable, this is why the cast works