Format in kotlin string templates

Question

Kotlin has an excellent feature called string templates. I really love it.

 val i = 10 
 val s = \"i = $i\" // evaluates to \"i = 10\"

But

Answer 1

Since String.format is only an extension function (see here) which internally calls java.lang.String.format you could write your own extension function using Java's DecimalFormat if you need more flexibility:

fun Double.format(fracDigits: Int): String {
    val df = DecimalFormat()
    df.setMaximumFractionDigits(fracDigits)
    return df.format(this)
}

println(3.14159.format(2)) // 3.14