Mastering High Performance with Kotlin

Fields and properties

In the preceding example, I used a special function, TODO(), from the Kotlin standard library. This function is overloaded and has two implementations:

@kotlin.internal.InlineOnlypublic inline fun TODO(): Nothing = throw NotImplementedError()@kotlin.internal.InlineOnlypublic inline fun TODO(reason: String): Nothing = throw NotImplementedError("An operation is not implemented: $reason")

It's very useful when you're modeling a class and don't want to implement certain class members right away. You can also use it for methods, as shown in the following code:

fun click() {   TODO()} 

And you can use it for constructors as well:

constructor() {   TODO()}

Let's look at how the Button class decompiled to Java:

public final class ...