Kotlin hash code builder with inline class

README.md

Previous example: https://gist.github.com/tanmatra/04b049a77918b8b321ba4c37f4c582c1

hashCode.kt

inline class HashCode(val value: Int = INIT)
{
    operator fun plus(any: Any?) = HashCode(MULTIPLIER * value + any.hashCode())

    operator fun plus(int: Int) = HashCode(MULTIPLIER * value + int)

    companion object {
        private const val INIT = 17
        private const val MULTIPLIER = 31
    }
}

inline fun buildHashCode(block: (HashCode) -> HashCode): Int {
    return HashCode().let(block).value
}

class Stat(
    val root: String,
    val data: Any,
    val devices: String,
    val id: Int = 55
) {
    override fun hashCode(): Int = buildHashCode { it + root + data + devices + id }

    override fun equals(other: Any?): Boolean = when {
        other !is Stat -> false
        root != other.root -> false
        data != other.data -> false
        devices != other.devices -> false
        id != other.id -> false
        else -> true
    }
}

fun main() {
    val stat1 = Stat("s1", "d1", "u1")
    val stat2 = Stat("s1", "d1", "u1")
    println("equals = ${stat1 == stat2}")
    println("hashCode = ${stat1.hashCode()}")
}