sbopt

sbopt is a little command line options builder library.

Motivation

Given the following values

val hour : Option[String] = Some("18")
val dryRun : Boolean = true

You want to build arguments to call another process

val hourArgs   = hour.map(v => Seq("--hour", v)).getOrElse(Nil)
val dryRunArgs = if (dryRun) Seq("--flag") else Nil
val allArgs    = hourArgs ++ dryRunArgs

with this library, you can simply do

args(opt("hour", hour), flag("dry-run", dryRun))

Usage

Here are some usages for building arguments :

• with a String option

@ args(opt("name", "value"))
ArrayBuffer("--name", "value")

• with an Int option

@ args(opt("name", 42))
ArrayBuffer("--name", "42")

• with an Option option

@ args(opt("name", Some("value")))
ArrayBuffer("--name", "value")

• with a List option (values are separated by a comma)

@ args(opt("name", List("A", "B")))
ArrayBuffer("--name", "A,B")

• with a Tuple option (values are separated by an equal)

@ args(opt("name", ("key", "value")))
ArrayBuffer("--name", "key=value")

• with 2 options

@ args(opt("name", "value"), opt("other", "XXX"))
ArrayBuffer("--name", "value", "--other", "XXX")

• with a repeated option

@ args(opt("name", "A"), opt("name", "B"))
ArrayBuffer("--name", "A", "--name", "B")

• with a repeated option, by using a dedicated helper

@ args(opts("name", List("A", "B")))
ArrayBuffer("--name", "A", "--name", "B")

• with an heterogeneous repeated option

@ args(opts("name", "value", 42))
ArrayBuffer("--name", "value", "--name", "42")

• putting it all together (a.k.a. calling spark-submit in a programmatic way)

@ args(opts("conf", ("verbose", true), ("spark.yarn.maxAppAttempts", 1), ("spark.yarn.jars", List(java.nio.file.Paths.get("/path1"), java.nio.file.Paths.get("/path2")))))
ArrayBuffer("--conf", "verbose=true", "--conf", "spark.yarn.maxAppAttempts=1", "--conf", "spark.yarn.jars=/path1,/path2")

• with a discardable (empty String or None) value

@ args(opt("name", ""))
ArrayBuffer()

@ args(opt[String]("name", None))
ArrayBuffer()

Built-in Supported Types

sbopt comes with support for many types, most of them from the standard Java and Scala libraries. When using those types, users don’t have to provide anything else in order to be able to build an argument.

The currently supported basic types are:

• String
• Boolean
• Int, Long, Float, Double
• java.io.File
• java.nio.file.Path
• Tuple2
• Option
• List

Supporting New Types

sbopt can be extended to support those types. To do so, an instance for the Encoder type class must be provided.

by implementing a new Encoder yourself

class WrappedString(val self: String)
implicit val wrappedStringEncoder: Encoder[WrappedString] = _.self

by using a from combinator

When you can convert your type to a type that has an instance of Encoder

class WrappedInt(val self: Int)
implicit val wrappedIntEncoder: Encoder[WrappedInt] = Encoder.from(_.self)