enum polymorphism implementation - kotlin

Question

Consider an interface:
interface class IPage {
}
and two enums implementing this interface as
enum class Page1 : IPage{ ..... }
enum class Page2 : IPage{ ..... }
Now I have a method
fun getPage(isSomeCondition : Boolean) : IPage{
if(isSomeCondition) return Page1
else return Page2
}
However I am getting a compile time error:
Classifier Page1 does not have a companion object and must be initialized here, I believe that is happening because of the interface, but I am out of ideas on how to solve it!
More explanation:
Both of these enums hold values which are similar, basis the boolean condition I want to load either of the enums and work on the values contained inside of that enum.
consider for example my enums with an updated signature:
enum Page1(val title: String, val data : Data)
Now my Data class has various implementations like ChildData | ParentData | FriendData etc
example:
enum Page1(val title: String, val data : Data){
PARENT("Heiachi", ParentData(...)),
CHILD("JIN", ChildData(...))
}
enum Page2(val title: String, val data : Data){
PARENT("Hworang", FriendData(...)),
CHILD("Yoshimitsu", FoeData(....))
}
Where
class ParentData : Data
class ChildData : Data
class FriendData : Data
class FoeData : Data

Answer 1

Maybe you want to iterate the children of the enum that you've been returning? If so, you can return the implementations of the enums, not the enum definitions:
fun getPage(isSomeCondition : Boolean) : Iterable<IPage>{
if(isSomeCondition) return Page1.values()
else return Page2.values()
}
Alternatively, you can make a class that defines a parent or child. You can then optionally store thes in a single enum or just make them conform to another interface.
class PageType(val title: String, val data : Data)
enum Page(val parent: PageType, val child: PageType) {
Page1(PageType("Heiachi", ParentData(...)), PageType(("JIN", ChildData(...))),
Page2(PageType("Hworang", FriendData(...)), PageType("Yoshimitsu", FoeData(....))
}
fun getPage(isSomeCondition : Boolean) : Page {
if(isSomeCondition) return Page.Page1
else return Page.Page2
}
// Alternative to enum:
interface Page {
val parent: PageType
val child: PageType
}
object Page1: Page {
override val parent = PageType("Heiachi", ParentData(...))
override val child = PageType(("JIN", ChildData(...))
}
object Page2: Page {
override val parent = PageType("Hworang", FriendData(...))
override val child = PageType(("Hworang", FoeData(...))
}