I have a class that takes a list of `Any` but the subtypes a kotlinlang #announcements

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Title

Paul Woitaschek

12/03/2018, 2:08 PM

I have a class that takes a list of

Any

but the subtypes are not directly related so they can't be sealed classes.

Alan Evans

12/03/2018, 2:20 PM

You can create a sealed wrapping type:

sealed class Wrapper{
   class TypeA(val value: A): Wrapper()
   class TypeB(val value: B): Wrapper()
   ...
}

Then accept

List<Wrapper>

and get the exhaustive

when

you probably are after.

Obviously there's probably a better name than

Wrapper

but I don't know your domain.

Paul Woitaschek

12/03/2018, 2:27 PM

That's too performance intensive unfortunatelly

If it were inline classes... 😉

Alan Evans

12/03/2018, 3:15 PM

One allocation per item is not going to break the bank! If you have a very large list already, then you likely already have these performance issues.

Paul Woitaschek

12/03/2018, 3:25 PM

No, but it doubles what's in the bank ^^

Alan Evans

12/03/2018, 3:55 PM

how so? It doubles the number of objects referred to by the list. But that doesn't mean double the memory, or double the processing time. What are we talking here, 100 items, 1000?

I guarantee you that if you profile your application, you will see far lower hanging fruit that worrying about a few object allocations. Profile, and optimize the inner loops, I would not optimize upfront like this, it is always a waste of time.

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