is there anyway to have something like this ``` fu...

# announcements

[Andrew Gazelka]

is there anyway to have something like this

fun <T> wrapperFunc(block: (…) -> T): (…) -> T{
    println("wrapped")
    return block (…) -> T
}

and call it like

val testFunc = wrapperFunc {
    fun(a: String) -> println("a is $a")
}

testFunc("abc")

[Luke]

Do you want the call to print to be called when you run testFunc("abc")?

[Andrew Gazelka]

yeah so testFunc("abc") would print to sout

wrapped
abc

[streetsofboston]

I don’t think that is possible without using reflection. The issue is the ..., like a vararg kind a thing, but each argument should be individually typed (and on top of that, i think that lambdas can take a vararg).

[Al Warren]

Not really the same but it might give you some ideas. I have an abstract class with this in it:

internal var clickListener: (T) -> Unit = { }

Then the concreted class does this:

setOnClickListener { clickListener(data) }

Finally, the calling class does this:

adapter.clickListener = ::onItemClick

[Luke]

You can have something like this: http://tiny.cc/fgwm9y. But yeah, you can’t be too general with parameters quantity and types

[Al Warren]

Oh, sry, I didn't take the ellipses to actually mean varargs. Nevermind. 😁

[bloder]

Maybe you can use other approach to that like compose your functions, actually is basically what you want there, no?

[streetsofboston]

@Andrew Gazelka
Something like this?

infix fun <R> (() -> Unit).andThen(function: () -> R) : () -> R = {
    this()
    function()
}

infix fun <T1, R> (() -> Unit).andThen(function: (T1) -> R) : (T1) -> R = {
    this()
    function(it)
}

infix fun <T1, T2, R> (() -> Unit).andThen(function: (T1, T2) -> R) : (T1, T2) -> R = { t1, t2 ->
    this()
    function(t1, t2)
}

infix fun <T1, T2, T3, R> (() -> Unit).andThen(function: (T1, T2, T3) -> R) : (T1, T2, T3) -> R = { t1, t2, t3 ->
    this()
    function(t1, t2, t3)
}

fun prefix() {
    println("wrapped")
}

fun functionToWrap(name: String, age: Int): String = "$name has age $age"

fun main() {
    val testFunc = ::prefix andThen ::functionToWrap
    println(testFunc("Jim", 45))
}

But, yes, for the vararg like functionality, you’d need to define more and more andThen functions, each one an extra Tn generic parameter.