Is there a way to reference `self` or something eq...

# announcements

[Stefan Peterson]

Is there a way to reference self or something equivalent in a constructor of a data class such that you could do something like:

abstract class A(abstract name: String?)

data class B(override val name: String? = self::class.simpleName): A()

val b = B()
print(b.name)        // B

[Shawn]

you can still use this in this case

[Shawn]

are you running into a type mismatch error if you do?

[Shawn]

simpleName is String? rather than String, so you’ll need a default or !! if you like living dangerously

[Stefan Peterson]

Ah whoops left something out of my example, I am implementing an interface and yes you are right about the optional

[Stefan Peterson]

Updated the code snippet to be more accurate, sorry about that.

[Shawn]

no worries

[Shawn]

ahh, you’re running into a different issue

[Shawn]

a couple of them actually

[Shawn]

you can’t have abstract properties in the constructor

[Shawn]

(doing so would make them concrete, not abstract)

[Shawn]

abstract class A {
    abstract val name: String?
}

data class B(override val name: String? = this::class.simpleName): A()

is valid

[bloder]

I'm trying using this but is showing me that this is not defined in this context, are u getting to do that with this?

[Shawn]

it’s evaluating just fine in a scratch file, let me double-check in a normal .kt lad

[Shawn]

ahh, it looks like I am the big dumb - this evaluates just fine within the scratch file because it resolves to the outer class that the scratch file code technically resides in

[bloder]

that's weird because I thought in a data class constructor I've already able to use its reference 🤔

[Shawn]

well, sort of, just not through this

[Shawn]

this works:

data class B(override val name: String? = B::class.simpleName): A()

[Shawn]

it makes sense that you can’t access this within the constructor because an instance hasn’t been instantiated yet

[Shawn]

also, just for the record (and those playing along at home), data classes are really not special in almost any regard except for autogenerated methods (toString(), equals(), hashCode(), copy(), and property-only constructors). they act just like regular classes in this instance and you should assume they do in most cases

[Stefan Peterson]

Ah yes I had discovers I could do it by doing B::class.simpleName was just hoping for something a little nicer. Thanks all. And yea I am using data class here specifically for the copy feature