Android - Switching fragments without recreating their instances - Kotlin Extension

Example.kt

...

sealed class Section
object Home : Section()
object Settings : Section()

...

private fun changeSection(section: Section) {
    if (currentSection == section) {
        return // nothing to do
    }
    currentSection = section
    when (section) {
        is Home -> supportFragmentManager.switchFragmentTo(R.id.fragment_container, "HOME") { HomeFragment() }
        is Settings -> supportFragmentManager.switchFragmentTo(R.id.fragment_container, "SETTINGS") { SettingsFragment() }
    }
}

...

SwitchFragmentExtension.kt

package cz.mvoda.ext

import android.support.v4.app.Fragment
import android.support.v4.app.FragmentManager

/**
 * Shows a Fragment according to the tag. If given fragment doesn't exist yet, then it's created 
 * and added with given tag.
 */
fun FragmentManager.switchFragmentTo(container: Int, tag: String, fragmentFactory: () -> Fragment) {
    var existing = findFragmentByTag(tag)
    if (existing == null) {
        // Not existing -> create new fragment instance and add it
        existing = fragmentFactory()
        beginTransaction().add(container, existing, tag).commit()
    } else if (!existing.isVisible) {
        // Added but not visible -> show fragment
        beginTransaction().show(existing).commit()
    } else {
        // Visible -> Nothing to do
        return
    }
    // Hide all other fragments
    fragments.filter { it.isVisible && it !== existing }.forEach { beginTransaction().hide(it).commit() }
}