How to best make a conversion method with a defaul...

# getting-started

[David Kubecka]

How to best make a conversion method with a default for the null receiver?

Currently, I have this:

data class A(param: Int)
data class B(param: Int) {
  fun toA() = A(param)
}

I want to make the converter work also on a nullable receiver providing some default value. I know I can do the following:

data class B(param: Int)

fun B?.toA() = this?.let { A(param) } ?: A(42)

but wonder whether there's a better option. At least if I can somehow keep the non-nullable toA inside the class definition (keeping its name) and refer to it in fun B?.toA().

UPDATE: I realize now I can indeed refer to original toA from B?.toA() . Still it doesn't look very nice...

[Thiago]

fun B?.toA(): A = A(this?.param ?: DefaultValue)

[David Kubecka]

Hmm, that seems to be better only in the single param case IMO 😞

Moreover, I'm maybe more interested in the option of keeping the converter inside the class def.

[Ruckus]

Are you saying
fun B?.toA() = this?.toA() ?: A(42)
doesn't look very nice? If so, I'm not sure I understand what you're asking.

[David Kubecka]

Yeah, that's not so horrible. As I said

I'm maybe more interested in the option of keeping the converter inside the class def.

[Ruckus]

Ah, I think I must have misread that part. The way I see it, that wouldn't make much sense, as, if the class def is available, that's basically what not-null means, though I can see how that's a rather circular argument.