Hi guys, so I have a question regarding lambdas: ...

# getting-started

[RoqueRueda]

Hi guys, so I have a question regarding lambdas:

I have a function like:

fun addVisibilityListener(listener: (Int) -> Unit = {})

I want to create a list of listeners, It is possible to have a list of lambdas? or how can I handle that scenario?

[arekolek]

val listeners = mutableListOf<(Int) -> Unit>()

fun addVisibilityListener(listener: (Int) -> Unit = {}) = listeners.add(listener)

addVisibilityListener {
    println("First listener got: $it")
}

addVisibilityListener()

addVisibilityListener {
    println("Third listener got: $it")
}

listeners.forEach { listener ->
    listener(0)
}

seems to work just fine

[RoqueRueda]

Thanks a lot I was not sure on what was the args for the <>!

[Matteo Mirk]

yes it’s totally possible, I’d recommend to use a typealias for improved readability

typealias Listener = (Int) -> Unit

val listeners = mutableListOf<Listener>()