Kotlin DSL Shadowing

kotlin-shadow.kt

data class SetFoo(val foo: Int)
data class SetFooAndBar(val foo: Int, val bar: Int)

fun setFooTo3AndBarTo42(exec: SetFooAndBar.() -> Unit) {
    SetFooAndBar(3, 42).exec()
}

fun setFooTo4(exec: SetFoo.() -> Unit) {
    SetFoo(4).exec()
}

fun main() {
    // Adds foo and bar into scope
    setFooTo3AndBarTo42 {
        println("Foo is ${foo}")
        println("Bar is ${bar}")

        // Leaves bar as it is, but shadows foo with a new value
        setFooTo4 {
            println("Foo is ${foo}")
	    println("Bar is ${bar}")
        }

        // Back to the old values
	println("Foo is ${foo}")
	println("Bar is ${bar}")
    }
}