Kotlin call function only if all arguments are not null

Question

Is there a way in kotlin to prevent function call if all (or some) arguments are null? For example Having function:

fun test(a: Int, b: Int) { /* function body here */ }

I would like to prevent null checks in case when arguments are null. For example, for arguments:

val a: Int? = null
val b: Int? = null 

I would like to replace:

a?.let { b?.let { test(a, b) } }

with:

test(a, b)

I imagine that function definition syntax could look something like this:

fun test(@PreventNullCall a: Int, @PreventNullCall b: Int)

And that would be equivalent to:

fun test(a: Int?, b: Int?) {
    if(a == null) {
        return
    }

    if(b == null) {
        return
    }

    // function body here
}

Is something like that (or similar) possible to reduce caller (and possibly function author) redundant code?

Answer 1

If you don't want callers to have to do these checks themselves, you could perform null checks in an intermediary function, and then call into the real implementation when they passed:

fun test(a: Int?, b: Int?) {
    a ?: return
    b ?: return
    realTest(a, b)
}

private fun realTest(a: Int, b: Int) {
    // use params
}

---

Edit: here's an implementation of the function @Alexey Romanov has proposed below:

inline fun <T1, T2, R> ifAllNonNull(p1: T1?, p2: T2?, function: (T1, T2) -> R): R? {
    p1 ?: return null
    p2 ?: return null
    return function(p1, p2)
}

fun test(a: Int, b: Int) {
    println("$a, $b")
}

val a: Int? = 10
val b: Int? = 5
ifAllNonNull(a, b, ::test)

Of course you'd need to implement the ifAllNonNull function for 2, 3, etc parameters if you have other functions where you need its functionality.