How to idiomatically unwrap multiple optionals (wi...

# announcements

[iex]

How to idiomatically unwrap multiple optionals (without nesting)?

[ribesg]

Create a function that does it

[iex]

ok... I guess just if (a != null && b != null) {...} is enough, because of smart cast

[iex]

ah right but that works only if I assigned vals already. Not e.g. retrieving values of a map

[ndv]

You could do something like this

fun example () {
	var a: Double? = null
	var b: Double? = null
	(a and b)?.let { (a, b) -> { /* Your function */ } }
}

infix fun Any?.and (other: Any?): Pair<Any, Any>? {
	return if (this != null && other != null) this to other else null
}

If you didn't want to rely on type casting, you could add generics, though it makes using an infix function a little less attractive. Now the types of both parameters are known:

fun example () {
	var a: Double? = null
	var b: Double? = null
	safeCombine(a, b)?.let { (a, b) -> { /* Your function */ } }
}

fun<A, B> safeCombine (a: A?, b: B?): Pair<A, B>? {
	return if (a != null && b != null) a to b else null
}

Can mess around with this sort of implementation to get your desired effect I think?

If they variables were all the same type you could expand it to use vararg and return a null safe collection

[iex]

@ndv thanks! for more than 2 pars vararg and list is not ideal though... but cool input nonetheless