JScript or Groovy syntax for swapping variables

1

Now to swap variables you have to do something like this:

    var a = 1
    var b = 2
    var c = 3

    println("$a $b $c")
    a = c.also { c=b.also { b = a } }
    println("$a $b $c")

which is not bad, but JScript and groovy ones are far better:

[a, b, c] = [c, a, b] - JScript
(a, b, c) = [c, a, b] - Groovy

May be this is a more general question of a variable multiple assignments?
But I generally want to show something to my JScript colleagues, which they do not have in their arsenal and by now they always shoot at me back with something better.

2

Do you have real example, where you need to swap variables? I can’t imagine a case, where it is not a consequence of bad design. Also, you example shows a clear abuse of also.

3

Swapping variables is shown as one of the main Idioms in the Kotlin documentation. https://kotlinlang.org/docs/reference/idioms.html

I think, that the fact that other languages (one of which is JVM based) are implementing this functionality, is more than enough proof, that there is a reason to do so and there is no reason for me trying to convince anyone.

4

May be the real question is; why there is no multiple assignment in Kotlin?

5

No, it is not. There is huge amount of bad practices in Python, JavaScript, Scala and even Java. It is not a reason to pull them into Kotlin.

6

May be you are right, but you can misuse any language feature so and so. Is this the real reason why this feature is not present in the language?

7

It is hard to say, what happens in heads of language committee, buy I assume that they do not see added value in it. I personally still do not see, where it could be massively applied.

8

I agree. From my perspective it does not overcome the minus 100 points that any feature starts with.

9

I thought maybe this destructuring would work:

var a = 1
var b = 2
(a, b) = Pair(b, a)

Since it works in Swift and the following works in Kotlin:

val (a2, b2) = Pair(b, a)

But I guess not.