Here is some code which does not work. I suspect that the reason that it does not work is that

this

in the

buildString

lambda does not refer back to the

ByteArray

, but instead to the implicit

StringBuilder

which is being built, and I suspect that the

forEach

is inheriting its iterator from the inner

this

, rather than the (shadowed) outer

this

. HOWEVER: the code is cute, and I would like understand the problem to be certain, and to save the situation. Can I elegantly fix the shadowing problem in the existing code, rather than refactoring it to use a loop, or

with

or

apply

?

const val INT_TO_HEX = "0123456789ABCDEF"
fun ByteArray.toHexStringDoesNotWork() = buildString {
    forEach {
        val octet = it.toInt()
        append(INT_TO_HEX[octet.and(MASK_UPPER_NIBBLE).ushr(4)])
        append(INT_TO_HEX[octet.and(MASK_LOWER_NIBBLE)])
    }
}

Try

this@toHexString.forEach

Awesome! That works. Thank you @Adam Powell

The same thing works any time you need to clarify a specific

this

in scope

Or simply

fun ByteArray.toHexString() = joinToString("") { it.toString(16).padStart(2, '0') }

🙂