Is there any way to make a function such as

handleBox

typecheck without unsafe casting?

but why you need to have the

abstract val value

in the first place ?

Isn't

box

smartcasted to

IntBox

?

yes it is, but the compiler doesn't realize that

T

has the same type as

box.value

Does something like

val box: Box = ...
if (box is IntBox)
    println(box.value * 2)

also not work?

that works fine, the problem is that

when(box) { .. }

has the return type

Any

instead of

T

Damm missed the return part, okay that makes sense.

1.3 added new type inference to better support intersection types

Int & String

, maybe we get sum types

Int | T

with 1.4? :trollface:

I remember there being a youtrack issue similar to this, can't find it though.

BTT, @toxara its not possible right now