Allow multiplying by Double, not just Int

[sargunv]

I'm doing this, to generate a list of stops for a scale bar on a map:

private fun buildStops(mantissas: List<Length>, exponents: IntRange) = buildList {
  for (e in exponents) for (m in mantissas) add(m * 10.0.pow(e))
}

val metricStops = buildStops(mantissas = listOf(1, 2, 5).map { it.meters }, exponents = -1..7)

It generates a list like

0.1 m
0.2 m
0.5 m
1 m
2 m
5 m
10 m
...
10000 km
20000 km
50000 km

but 10.0.pow(e) is a Double, and this library only has an operator overload for Length x Int. So I needed to add this helper:

private operator fun Length.times(other: Double) =
  (this.toLong(LengthUnit.International.Nanometer) * other).roundToLong().nanometers

Such a helper should probably be provided by the library. Looking at kotlin.time.Duration, they already have this:

public operator fun times(scale: Double): Duration {
    val intScale = scale.roundToInt()
    if (intScale.toDouble() == scale) {
        return times(intScale)
    }

    val unit = storageUnit
    val result = toDouble(unit) * scale
    return result.toDuration(unit)
}

If this is acceptable, I'd be happy to PR it.

[kevincianfarini]

I think we'd actually want this implemented on SaturatingLong so that it can be used anywhere. Want to take a stab at that?

[kevincianfarini]

Actually, I take that back. The sample from Duration looks sufficient for implementing on quantities. Mind PRing for all the types?

[sargunv]

Will do