I found a way to make it work but it seems wrong minded:
class C {
var i = 0
var j = 0
var k = 0
def mv: (Int,Int,Int) = {
(1,2,3)
}
def changeState: Unit = {
val (x,y,z) = mv
i = x
j = y
k = z
}
}
val c = new C
c.i == 0 //true
c.changeState
c.i == 1 //true so this works
So it works but is ugly