How to destructure a Pair object into two variables in Kotlin

Question

I have a function that returns Pair:

fun createTuple(a: Int, b: Int): Pair<Int, Int> {
    return Pair(a, b)
}

I want to initialize variables a and b using this function and then reassign them inside loop:

var (a, b) = createTuple(0, 0)
for (i in 1..10) {
    createTuple(i, -i).let{
       a = it.first
       b = it.second
    }
    println("a=$a; b=$b")
}

Using let seems awkward. Is there a better way to unwrap Pair inside loop?

The following lines do not compile:

(a, b) = createTuple(i, -i)
a, b = createTuple(i, -i)

Pillbox

Destructuring assignment is not supported. There's an open issue for it on the tracker that's a few years old. If you use run instead of let, you can drop the its. – Liselisetta

Your question is very unclear on what you want to achieve. Here, you could just do for (i in 1..10) { a = i; b = -i } – Carleecarleen

@SiddharthSharma it is a minimal example. My question was about destructuring assignment and Tenfour04 answered it – Pillbox

@Pillbox Haha okay, then your question could have been a lot more minimal. For example, "How to destructure a Pair object into two existing variables" – Carleecarleen

Answer 1

var (a, b) = createPair(0, 0) compiles fine for me.

Your problem probably is using createTuple(i, -i) instead of createPair(i, -i).

Maxine

Sorry, it was a copy/paste error. My answer was about destructuring assignment, see Tenfour04 comment – Pillbox

Too bad this is only supported for local variables: "Destructuring declarations are only allowed for local variables/values" I'd like to declare two class members in one step: val (a,b) = createPair(0,0) – Miller