Kotlin: how to pass a function as parameter to another?

Question

Given function foo :

fun foo(m: String, bar: (m: String) -> Unit) {
    bar(m)
}

We can do:

foo(\"a message\", { println         


        

Answer 1

About the member function as parameter:

1. Kotlin class doesn't support static member function, so the member function can't be invoked like: Operator::add(5, 4)
2. Therefore, the member function can't be used as same as the First-class function.
3. A useful approach is to wrap the function with a lambda. It isn't elegant but at least it is working.

code:

class Operator {
    fun add(a: Int, b: Int) = a + b
    fun inc(a: Int) = a + 1
}

fun calc(a: Int, b: Int, opr: (Int, Int) -> Int) = opr(a, b)
fun calc(a: Int, opr: (Int) -> Int) = opr(a)

fun main(args: Array) {
    calc(1, 2, { a, b -> Operator().add(a, b) })
    calc(1, { Operator().inc(it) })
}