I don't think this is possible, but I figured I wo...

# announcements

[blakelee]

I don't think this is possible, but I figured I would ask anyway. Is it possible to chain together multiple enum class into a builder pattern sort of deal

For instance I have something like this

enum class Page {
    PAGE_1,
    PAGE_2;
}

enum class Page1Section {
    SECTION_A,
    SECTION_B
}

enum class Page2Section {
    SECTION_1,
    SECTION_2
}

With my end goal being something like

Page.PAGE_1.SECTION_A.build()

and if I selected PAGE_2 then

Page.PAGE_2.SECTION_1.build()

Maybe this would be better in sealed classes

If I selected PAGE_1, if I were to type . then I would get the list of Page1Section's then if I click . again perhaps another list of items

[Nir]

PAGE_1 and PAGE_2 are the same type so I don't off the top of my head see how you could get different completions

[Nir]

but yeah, as you say, sealed classes would work here

[Matteo Mirk]

I don’t know about enums but what you’re after looks a lot like the Type-safe Builder pattern to me: https://www.endoflineblog.com/type-safe-builder-pattern-in-java-and-the-jilt-library
It allows you to take advantage of the type system to guarantee the correctness of a builder’s usage.
But maybe sealed classes would be better suited in this case.

[Nir]

why would you use the builder pattern in kotlin when you have keyword arguments?

[Matteo Mirk]

of course I wouldn’t use it in Kotlin, since we have named and default args, but the OP request looked familiar to what the Type-safe Builder pattern (different from the standard one) can accomplish, so I thought it could be adapted to his use case