is there a way to create an extension function for...

# announcements

[Jon]

is there a way to create an extension function for an annotated data class?

[karelpeeters]

Not really, neither "annotated" nor "data class" are represented by the type system.

[Shawn]

yeah, data classes don’t inherit from anything but Any or implement any kind of interface by default, just like any other class

[tschuchort]

Theoretically you could generate them using an annotation processor

[Jon]

Thanks for the help. Is there a way to create an extension function on "Any" that has been annotated in some way?

[Jon]

I was reading https://kotlinlang.org/docs/reference/annotations.html#annotation-use-site-targets, and it seems like it is possible

[Shawn]

you can annotate a lot of things, but based on this conversation I don’t think it’ll necessarily do what you want it to

[Dominaezzz]

Consider using an interface instead of an annotation.

[Jon]

Thanks. Maybe I should elaborate a bit more on my problem. So I am using kotlin's Json serializer to convert my data classes to a json string. I have code that looks like this sprinkled all throughout my code base (Json(JsonConfiguration.Stable).stringify(myType.serializer(), myType(a, b, c)) . I thought it would be nice to just create an extension function on my data class where I can do: myType(a,b,c).toJson()

[Shawn]

Would you mind clarifying what you mean by “kotlin’s JSON serializer?”

[Shawn]

there are a number of them usable from Kotlin is all 😅

[Jon]

hah, sure 🙂

[Jon]

this one https://github.com/Kotlin/kotlinx.serialization/blob/master/docs/examples.md