Kotlin - idiomatic way to create a Fragment newInstance pattern

Question

The best practice on Android for creating a Fragment is to use a static factory method and pass arguments in a Bundle via setArguments()

Answer 1

Late to the party, but I believe Idiomatically it should be something like this:

private const val FOO = "foo"
private const val BAR = "bar"

class MyFragment : Fragment() {
    companion object {
        fun newInstance(foo: Int, bar: String) = MyFragment().withArgs {
            putInt(FOO, foo)
            putString(BAR, bar)
        }
    }
}

With an extension like this:

inline fun  T.withArgs(argsBuilder: Bundle.() -> Unit): T =
    this.apply {
        arguments = Bundle().apply(argsBuilder)
    }

or

companion object {
    fun newInstance(foo: Int, bar: String) = MyFragment().apply {
        arguments = bundleOf(
            FOO to foo,
            BAR to bar
        )
    }
 } 

The key being that the private constants should not be part of the companion object.