With Kotlin 1.5, the sealed interface was introduced. Even though I know the difference between classes and interfaces, I'm not clear on the best practices and benefits of using a sealed interface over a sealed class.
Should I always use interface now, even in simple cases, or will it depend on the specific situation?
Thanks!
P.S. I didn’t find similar questions, only those about sealed classes.
A major reason to choose to use a sealed class instead of interface would be if there is common property/function that you don't want to be public. All members of an interface are always public.
The restriction that members must be public can be worked around on an interface using extension functions/properties, but only if it doesn't involve storing state non-publicly.
Otherwise, sealed interfaces are more flexible because they allow a subtype to be a subclass of something else, an enum class, or a subtype of multiple sealed interface/class hierarchies.