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Named Arguments

What exactly are named arguments?​

It's a way of saying exactly what parameter you're targeting when passing a value or values to a function

How does it work ?​

fun read(book: String, line: Int, library: String = "any", page: Int = 1,){
    println("Library = $library | Book = $book | Page = $page | Line = $line")
}

read(book = "Think Fast", page = 120)

> Library = any | Book = Think Fast | Page = 1 | Line = 120

In the example above book and page are named arguments You're telling the compiler explicitly the value for book is "Think Fast" and for page is 120

tip

when you declare a named argument ensure that every argument after it is also named to avoid future issues and confusion

Okay, but what is it's usecase?​

Named arguments helps when a funtion has too many arguments and you want to make it more readable among other things. Let's look at an example, say we have a list and we want to print it's contents

val list = listOf(1,2,3)
println(list.joinToString(",", "(", ")"))

Without printing the value you wouldn't know what is the separator and what encases the list. So here's where named arguments come along

val list = listOf(1,2,3)
println(list.joinToString(separator = ",", prefix = "(", postfix = ")"))

Now it is clear that the list starts with an opening parenthesis ( and after each item it adds a comma , as a separator finally finishes with the closing parenthesis ) to print : 

> (1,2,3)

You can find more usages in other bits, so keep on browings and add a reaction below or comment 😉 😉...