```sealed class BaseViewEffect{ object ShowView : BaseViewEffect() } sealed class ChildViewEffe...

# announcements

[Rohit Singh]

sealed class BaseViewEffect{
    object ShowView : BaseViewEffect()
}

sealed class ChildViewEffect : BaseViewEffect {
    
}

anyone can help me to achieve inheritance for sealed class

[Rohit Singh]

@jw any ideas to solve this use case?

[ghedeon]

On a side note, @jw would you make me a sandwich? I thought I might as well give it a try, since you're on a speed dial for everything.

[jw]

Sure what protein? White or wheat bread? Provolone or Swiss? What toppings? Toasted?

[diesieben07]

@Rohit Singh Your code worked fine for me. What is your problem exactly?

[Dico]

The problem is that you cant have inheritance of sealed classes without putting the children inside the sealed class. I would prefer the ability to have them in the same file :/

[Fredrik Larsen]

That was true before Kotlin 1.1, but now it works as long as it is in the same file. https://kotlinlang.org/docs/reference/sealed-classes.html

[Dico]

That's weird, I've had the problem of not being able to do this recently.

[Dico]

Well, I tried it and it works. I must have imagined it.

[Dico]

Ah no, theres something that does not work.

[Dico]

Example:

sealed class MySealedClass {
    open val length get() = 0
    
    class SpecialBlock(override val data: ByteArray) : SpecialVariants()
    
    sealed class SpecialVariants : MySealedClass() {
        abstract val data: ByteArray
        override val length get() = data.size
    }
}

[Dico]

SpecialBlock can't inherit from SpecialVariants

[Dico]

bug report?

[Dico]

https://youtrack.jetbrains.com/issue/KT-13495

[Fredrik Larsen]

You can flatten the hirearchy.

[Fredrik Larsen]

sealed class MySealedClass {
    open val length get() = 0
}

sealed class SpecialVariants : MySealedClass() {
    abstract val data: ByteArray
    override val length get() = data.size
}

class SpecialBlock(override val data: ByteArray) : SpecialVariants()

[Dico]

I understand that there's a workaround, I still would consider this inconsistent.

[Dico]

For me the workaround was to use abstract instead of sealed, sadly.

[Fredrik Larsen]

Fair enough. I still don't see the issue with flattening though. If you use abstract you lose compile time information about the hierarchy.

[Dico]

I have a preference to keep the file to 1 declaration as that is cleaner in the IntelliJ project view.

[Fredrik Larsen]

I see.

[Dico]

Sometimes I add more declarations, collecting connected stuff in one file, but often I keep it down to one.

[Rohit Singh]

@diesieben07 please read the messages above 👆

[diesieben07]

I did... Why?

[Rohit Singh]

It only works when parent class is in same file

[diesieben07]

Yes, that's how sealed classes work...

[Rohit Singh]

yeah just wanted to know if its possible to have it in different file and work

[diesieben07]

Since sealed classes are specifically designed to not allow that the answer is no.