Android Kotlin smart operator overloading

Issue

What if overload some Kotlin operator and use it like this:

// Inits somewhere before usage.
val someStrFromServer: String? 
lateinit var myFieldText: TextView

override fun onStart() {
    super.onStart()
    myFieldText.text = someStrFromServer / R.string.app_none
}

Operator overloading:

operator fun String?.div(resId: Int): String {
    return if (this.isNullOrBlank()) {
        context.getString(resId)
    } else {
        this
    }
} 

Output if someStrFromServer null:

D/DEBUG: None

Output if someStrFromServer not null:

D/DEBUG: someStrFromServer

Does anyone know, if in Kotlin exists a more efficient and short way to handle this? Perhaps, even more, global, like extension function.

Solution

You can do that, but it's not very intuitive because the div is normally used in mathematical calculations only. I'd recommend to use something like

someStrFromServer.takeUnless { it.isNullOrBlank()} ?: context.getString(resId)

Or simplified via extension

fun String?.fallback(resId: Int) = takeUnless { it.isNullOrBlank()} ?: context.getString(resId)

used like this:

myFieldText.text = someStrFromServer.fallback(R.string.app_none)

Answered By - s1m0nw1