Is it possible to access an extension property giv...

# getting-started

[Joshua Hansen]

Is it possible to access an extension property given this setup?

fun main() {
    val book = Book("Kotlin Basics", List(10) { Page(it + 1) })
    
    val p = book.pages[4] // get the fullName from this scope given `book` and `p`?
}


class Book(val name: String, val pages: List<Page>) {
    val Page.fullName: String
        get() = "$name: Page $number of ${pages.size}"
}

class Page(val number: Int)

[Youssef Shoaib [MOD]]

Yes, simply do:

fun main() = with(Book("Kotlin Basics", List(10) { Page(it + 1) })) {
    val p = pages[4]
    println(p.fullName)
}


class Book(val name: String, val pages: List<Page>) {
    val Page.fullName: String
        get() = "$name: Page $number of ${pages.size}"
}

class Page(val number: Int)

This also works with context parameters!

[Joshua Hansen]

Don't know why I didn't think of that, thanks!

[Klitos Kyriacou]

But do you really want to define it like this? The Page.fullname getter function has an implicit parameter (a receiver) that references the Book but you're not using it. If you don't need such a receiver, consider defining fullname outside of Book or in a companion object.

[Youssef Shoaib [MOD]]

@Klitos Kyriacou It is being used! name and pages both come from Book.

[Klitos Kyriacou]

Indeed they do, sorry for the noise.