I don’t understand why this works: val UInt.l...

# announcements

[Travis Griggs]

I don’t understand why this works:

val UInt.le_ubytes:UByteArray get() {
val quad = (0 until 31 step 8 ).map { shift -> (this shr shift and 0xFFu).ubyte }
return quad.toUByteArray()
}

but this doesn’t work:

val UInt.le_ubytes:UByteArray get() {
val quad = (0 until 31 step 8 ).map { shift -> (this shr shift and 0xFFu).ubyte }
return ubyteArrayOf(*quad)
}

It hates on the ubyteArrayOf() with the spread operator. It wants a UByteArray as the argument. Which is pointless, because why would I be using the ubyteArrayOf() helper if I had a UByteArray already?

[Evan R.]

I believe that’s because .map() returns a list, not an array. The spread operator only works on arrays, so the following would work:

val UInt.le_ubytes:UByteArray get() {
    val quad = (0 until 31 step 8 ).map { shift -> (this shr shift and 0xFFu).ubyte }
    return ubyteArrayOf(*(quad.toTypedArray()))
   }

[Travis Griggs]

thank you. that’s the hidden bit of sauce i was looking for (spread only works on arrays, not lists)