Kotlin - function, Lambda, Reflection

:: (Reflection) 

참조로 이해하면 되겠다. 즉 직접적인 함수 호출, 속성 접근이 아니다.

 

Reflection

 

Reflection | Kotlin

 

아래 코드는

function, extention, lambda 선언과 Reflection 사용 예이다.

// normal function
fun normalfunctionPrintSquare(a: Int): Unit {
    println(a * 2)
}

// single-expression function
fun singleexpressionfunctionPrintSquare(a: Int): Unit = println(a * 2)

// generic function
fun <T: Int> genericfunctionPrintSquare(a: T): Unit {
    println(a * 2)
}

// extention function
fun Int.printSquare(): Unit {
    println(this * 2)
}

// extention property
val Int.Square: Int
    get() = this * 2

// lambda
val lambdaPrintSquare = { t: Int -> println( t * 2 ) }

// My class 
class MyInt() {
    var square: Int = 5
        get() = field * 2

    fun printSquare(a: Int): Unit {
       println(a * 2)
    }
}


/* client code */
fun myfunc(printSq: (Int) -> Unit) {
    printSq(5)
}

fun main() {

    // myfunc(::lambdaPrintSquare)  // compile error
    myfunc(lambdaPrintSquare)

    //myfunc(normalfunctionPrintSquare) // compile error
    myfunc(::normalfunctionPrintSquare)
    myfunc(::singleexpressionfunctionPrintSquare)
    myfunc(::genericfunctionPrintSquare)

    // extention property reference
    println(Int::Square.get(5))

    // extention function call
    5.printSquare()

    // class method
    val intSq: (MyInt, Int) -> Unit = MyInt::printSquare
    intSq.invoke(MyInt(), 5)

    // class property
    val s = MyInt::square
    println(s.get(MyInt()))
}