Spark - feature warnings

Question

I am working through the examples in Spark in Action, and there was an example about implicit conversions in Scala, with code like this:

class ClassOne[T](val input: T) { }

class ClassOneStr(val one: ClassOne[String]) {
    def duplicatedString() = one.input + one.input
}
class ClassOneInt(val one: ClassOne[Int]) {
    def duplicatedInt() = one.input.toString + one.input.toString
}
implicit def toStrMethods(one: ClassOne[String]) = new ClassOneStr(one)
implicit def toIntMethods(one: ClassOne[Int]) = new ClassOneInt(one)

I input these lines into the spark shell, but after each of the implicit defs I get a warning like this:

warning: there were 1 feature warning(s); re-run with -feature for details

It still seems to work, but what does the warning mean?

but not sure what it means, does it mean rerun spark with `spark-shell -feature`? — b_pcakes, Jun 19 '16 at 01:05
scalacOptions ++= Seq("-feature") - need to add that to the build def file. — Isaiah4110, Jun 19 '16 at 01:50
Possible duplicate of [Re-run with -feature for details](http://stackoverflow.com/questions/23926515/re-run-with-feature-for-details) — Yuval Itzchakov, Jun 19 '16 at 08:51

score 2 · Accepted Answer · edited May 23 '17 at 10:27

2

You have to add

scalacOptions += "-feature"

to your build.sbt and execute reload if your sbt console is running (or restart it).

as mentioned here and here.

edited May 23 '17 at 10:27

Community

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answered Jun 19 '16 at 01:43

gsamaras

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Spark - feature warnings

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