Hello everyone, does anyone know, why the first f...

# announcements

[zeugederunity]

Hello everyone,

does anyone know, why the first four functions return false?

fun main() {
    fun main() {
    val arr1 = Array(0) { "" }::class
    val arr2 = arrayOf("")::class
    val arr3 = Array::class

    println(arr1 == Array::class)               //false
    println(arr1.isSubclassOf(Array::class))    //false
    println(arr2 == Array::class)               //false
    println(arr2.isSubclassOf(Array::class))    //false
    println(arr3 == Array::class)               //true
    println(arr3.isSubclassOf(Array::class))    //true
}

I think thats a bug.

[spand]

Why dont you inspect arr1 and it might become obvious

[zeugederunity]

Did that, all have the qualified name kotlin.Array
And all of them should be of class kotlin.Array.

[spand]

val arr1: KClass<out Array<String>>
val arr2: KClass<out Array<String>>
val arr3: KClass<Array<*>>

[zeugederunity]

Is it somewere documented that there is no type erasure in generics like array or lists in JVM?
Thats quite inconvenient, especially when you are working with a commons library.

[zeugederunity]

btw. that doesn't change my comment. If both KClasses are from type kotlin.Array they shoud return true when you call equals. Especially when you cant call isArray

[zeugederunity]

nvm. found the issue

[spand]

I think you have multiple misunderstandings. Maybe what you want to test is assignability between the types which is not limited to subclass of and equal class objects.

[zeugederunity]

No, i just want to check if an object instance is of the type Array in my MPP project in my commons code.

This is a simplified example of my code:

inline fun <reified T> T.call(block: (T)->Unit){
    if (T::class == Array::class){
        error("This is an array")
    }
    block(this)
}

In javascript that code works as expected, but when i use the same function in my JVM code it does not work as expected.

[zeugederunity]

that error occurs due to the fact, that in the JVM the arrays are mapped to their JVM counterparts, which are not subject to type erasure.
-> They have different Class tokens.