I'm wrapping a DoubleArray with the value class, but when the values of the same content compare, it...

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[RE]

I'm wrapping a DoubleArray with the value class, but when the values of the same content compare, it return false

[Stephan Schroeder]

so the equals-method of DoubleArray is broken?? 🤔 (since value/inline classes simply delegate to the class they wrap )

[Stephan Schroeder]

Indeed

fun main() {
    val d1 = DoubleArray(2){it.toDouble()}
    val d2 = DoubleArray(2){it.toDouble()}
    println(d1==d2)
}

prints false .
https://pl.kotl.in/4W5_kBvI_

[Stephan Schroeder]

well, it's not a data class, so good old java reference equality is to be expected I guess.

[Rob Elliot]

Arrays do identity equality on the JVM as I recall. You have to use Arrays.equals to compare them by their values.

[Stephan Schroeder]

true, but to come back to the original question, it doesn't look like you can override the equals-method of value classes. I tried it here: https://pl.kotl.in/6gMuO7zh3 with

@JvmInline
value class DAWrapper(
    val doubles: DoubleArray
) {
    override fun equals(other: Any?): Boolean {
        if(other !is DAWrapper) return false
        return Arrays.equals(doubles, other.doubles)
    }
}

and get the compile error Member with the name 'equals' is reserved for future releases

[Stephan Schroeder]

looks like you have to use a data class for now

data class DAWrapper(
    val doubles: DoubleArray
) {
    override fun equals(other: Any?) =
      other is DAWrapper &&
      Arrays.equals(doubles, other.doubles)
}

[Klitos Kyriacou]

Yes, see https://stackoverflow.com/a/71494364/13963086