Mastering Kotlin

Functional variables

Let's quickly refresh how to work with function variables. We can define a variable with a functional type like this:

var onClickHandler: (ViewState) -> Unit = {}

We can then reassign that stored function as with any other variable:

fun main() {    onClickHandler = { viewState ->        println("viewState -> ${viewState.title}                 ${viewState.subtitle}")    }}

And finally, since the variable represents a function, we can invoke the function in several different ways by referencing the variable name, as follows:

fun main() {    onClickHandler = { viewState ->        println("viewState -> ${viewState.title}                 ${viewState.subtitle}")    }        val viewState = ViewState("Hello", "Kotlin")    onClickHandler(viewState)    onClickHandler.invoke(viewState)}

By allowing ...