I have a data class MyDTO that takes several parameters, but in one place where I call it, some parameters are the same. At the moment, I have a function that looks like this:

fun createDTO(f: Foo): MyDTO {
    val a = f.foo()
    val b = f.bar()
    val c = f.baz()
    return MyDTO(a, a, b, c, b, c)
}

Is there a more succinct way to do this? I especially like expression bodies, but I can’t do this:

fun createDTO(f: Foo) = MyDTO(f.foo(), f.foo(), f.bar(), f.baz(), f.bar(), f.baz())

because foo, bar and baz are expensive and/or have side-effects, and therefore should only be called once.

I was thinking along the lines of:

data class MyDTO(val x1: Int, val x2: Int, val y1: Int, val y2: Int, val z1: Int, val z2: Int)

fun createDTO(f: Foo) = MyDTO(f.foo(), x2, f.bar(), f.baz(), y1, y2)

but of course I can’t access the properties of MyDTO until I’ve finished creating the instance.