call

Learn dynamic calls with KFunction.call.

Calling functions with call

You can call a function at runtime with KFunction.call(args...) or invoke(args...). Arguments are passed in order.

Example: fun double(n: Int): Int = n * 2. val fn = ::double. fn.call(5) returns 10. fn.invoke(7) gives the same result. This pattern calls function references dynamically.

invoke vs call

invoke and call are functionally the same; both call the KFunction. invoke is declared as an operator function; it can be called as fn(args).

Example: val fn = ::double. fn.invoke(5) and fn(5) give the same result. call is more explicit; invoke gives a shorter syntax. Both do runtime type checks; wrong argument count throws.

Exercise Call double with call

Define fun double(n: Int): Int that returns n * 2. In main take the reference val fn = ::double and print fn.call(5) and fn.invoke(7) on separate lines with println.

Show example solution

fun double(n: Int): Int {
    return n * 2
}

fun main() {
    val fn = ::double
    println(fn.call(5))
    println(fn.invoke(7))
}

Test yourself

Which method calls a KFunction at runtime?
- apply()
- let()
- call()
- also()
Show answer

call() — call() invokes a KFunction.
Match the call parts

::double

Function reference
fn.call(5)

Call
fn.invoke(7)

Operator call
10

Result

Complete the call

val fn = ::double
val r = fn.____(5)

Show answer

val fn = ::double
val r = fn.call(5)

Next lesson: Annotations

We Are Enhancing Your Experience

Cookie Preferences

Strictly Necessary Cookies

Analytical Cookies