Exmaples of 5 Kotlin Scoping functions, Run, With, Let, Apply, Also

Scoping Functions.kt

class ScopingFunctions {

    fun main() {
        val firstPerson = Person("Prokash", 28, "Programmer")
        val secondPerson = Person("Elizabeth", 34, "Singer")

        //Calls the specified function block with this value as its receiver and returns its result.
        run {
            if (firstPerson.age > secondPerson.age) firstPerson else secondPerson
        }.printPerson()

        //Extension Function
        //Calls the specified function block with this value as its receiver and returns its result.
        firstPerson.run {
            age += 1
            "Age is now $age"
        }.println()

        //Calls the specified function block with the given receiver as its receiver and returns its result.
        with(firstPerson) {
            age += 1
            "Age is now $age"
        }.println()

        //Calls the specified function block with this value as its argument and returns its result.
        firstPerson.let {
            it.age += 1
            "Age is now ${it.age}"
        }.println()

        //Calls the specified function block with this value as its receiver and returns this value.
        //Returns the original object after modification
        firstPerson.apply {
            age += 1
            profession = "Engineer"
        }.printPerson()

        //Calls the specified function block with this value as its argument and returns this value.
        //Returns the original object after modification
        firstPerson.also {
            it.age += 1
            it.profession = "Developer"
        }.printPerson()
    }

    data class Person(var name: String, var age: Int, var profession: String) {
        //fun printPerson() = println(this.toString())
    }

    fun Person.printPerson() = println(toString())

    fun String.println() = println(this)

    fun Int.println() = println(this)

}