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Why does ```data class Foo(val foo: Nothing? = nul...
# scripting
v
Why does
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data class Foo(val foo: Nothing? = null) {
    companion object {
        fun foo() {
            println(__FILE__)
        }
    }
}
fail compilation with
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error: object Companion captures the script class instance. Try to use class or anonymous object instead
and is there a way to mitigate it?
i
In K1, you should imagine the script body as some class initializer. Properties you have inside the script are this class' properties, classes you have are this class' inner classes. So it's compiled to something like
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class C(val __FILE__: File) {
    inner data class Foo(val foo: Nothing? = null) {
        companion object {
            fun foo() {
                println(__FILE__)
            }
        }
    }
}
And of course you can't access class' properties from its companion (or its inner class companion). There is basically no way to mitigate this in K1 (unless you don't refer script properties from companion)
v
In the actual case I don't. There I call a function that uses 
__FILE__
in the default value of a parameter of 
Foo
and in the companion object I call that constructor, but that also counts as referring. 😞
I hoped 
__FILE__
would be someway different and could be used anywhere in the file.
i
Yes, that's because functions are also methods of the class, and you can't refer them in companion objects(
v
I don't, I call the constructor and its default value calls the function. But I'm nitpicking. 😄
😁 1
i
So you basically can refer a property if you have an instance. And it even works with scripts. You can try if you wish...
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class Foo {
    companion object {
        fun foo(obj: Any) {
            val f = // obtain __FILE__ property of obj with reflection 
            println(f)
        }
    }
}


Foo.foo(this)
v
Nah, don't think so, but thanks. 😄
But still imho 
__FILE__
should be special and available in the whole file.
You said with K1 this will not work. How will it be different with K2? Wouldn't the same limitation apply?
Ha, thank god you lied to me. 😄
Extension function / property ftw.
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data class Foo(val foo: Nothing? = null) {
    companion object
}

fun Foo.Companion.foo() {
    println(__FILE__)
}
i
Yes, the capturing of the script instance (which is needed to access the provided properties, and the 
__FILE__
is just that) is limited by the language rules, in particular singletons cannot capture anything. The extension functions are not limited, of course. This limitation is arising on the translation to the JVM, and so far I don't see how we can overcome it in the K2 too, so probably it will remain a limitation at least in the initial K2 support. Theoretically, we can try to make 
__FILE__
a special value that is not limited by these rules, but I'm not yet sure it is important enough to spend an effort on. Anyway, it would be helpful if you'll file an issue about 
__FILE__
in YT.
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