Is there a way to ensure a generic type is a data ...

# announcements

[Danilo Herrera]

Is there a way to ensure a generic type is a data class?

[Danilo Herrera]

I was trying to create a copy of a generic value which was only meant to be a data class

[Ruckus]

only meant to be a data class

Why? what's significant about a data class? Ultimately they're just normal classes with some functions generated for you, and even those functions can be overridden, so being a data class doesn't really get you anything.

[Danilo Herrera]

I suppose. I guess I was trying to clone a generic type, and know that data classes have the copy method.

[Dominaezzz]

You could always make a interface Copy<T> { fun copy(): T }. Not sure how nicely it'll play with data classes though.

[streetsofboston]

Problem with the interface Copy, the copy function of a data class has an unknown signature, except for its name and return type

[Danilo Herrera]

I see. That makes sense. Ended up using this interface:

interface Cloneable<T> {
    fun clone(): T
}

which in turn makes the data classes have this implementation:

data class User(val id: String) : Cloneable<User> {
    fun clone() = copy()
}

[karelpeeters]

You can get a bit more type safety with interface Cloneable<T: Clonable<T>>