Kotlin invoke()

1 개요

Kotlin invoke()

class Invokable {
    var numberOfInvocations: Int = 0
        private set
    operator fun invoke(): Invokable {
        numberOfInvocations++
        println("numberOfInvocations=${numberOfInvocations}");
        return this
    }
}
fun invokeTwice(invokable: Invokable) = invokable()()
fun main(args: Array<String>) {
    invokeTwice(Invokable())
    // numberOfInvocations=1
    // numberOfInvocations=2
}

class Foo {
    var count = 0;
    operator fun invoke(): Foo {
        count++
        return this
    }
}
fun main(args: Array<String>) {
    val foo = Foo()
    foo()()()()()
    println("foo.count=${foo.count}")
    // foo.count=5
}

class Foo {
    var count = 0;
    operator fun invoke(): Foo {
        count++
        return this
    }
}
fun invokeTwice(foo: Foo) = foo()()
fun main(args: Array<String>) {
    val foo1 = Foo()
    val foo2 = invokeTwice(foo1)
    println("foo1.count=${foo1.count}") 
    // foo1.count=2
    println("foo2.count=${foo2.count}")
    // foo2.count=2
}

2 참고

• https://dzone.com/articles/learning-kotlin-invoke