getopt-scala

GNU GetOpt-style command line argument parsing for Scala.

Usage: OptMain (Since 1.1.0)

The easiest way to use getopt-scala is through having your main class extend fi.helsinki.cs.nodes.util.OptMain. You need to define val shortOptions:String, val longOptions:Seq[String], so that OptMain knows which options your program takes. The syntax of these is inspired by the Python getopt module: https://docs.python.org/3/library/getopt.html . You must not define a main() function. This is used by OptMain to parse the command line arguments. You need to define optMain(), which will be called from OptMain.main after parsing the command line arguments. You can then use these functions:

• mandatoryOption(String): String, requires the given option to be present on the command line and returns its value.
• optional(String): Option[String], returns the value of the given option if present on the command line. Otherwise returns None.
• optionSet(String): Boolean,returns true if the given on/off flag was present on the command line.

See https://github.com/lagerspetz/getopt-scala/blob/master/examples/src/main/scala/fi/helsinki/cs/nodes/examples/OptMainUsageExample.scala for a complete example.

Usage: Using ScalaGetOpt directly (Since 1.0.0)

If you want to parse command line arguments somewhere else than your main function, or just want to use ScalaGetOpt directly, you can extend ScalaGetOpt and call:

getOpt(args: Array[String], shortOptSpec: String = "", longOptSpec: Seq[String] = Seq.empty)

This function returns a Map[String, String] containing option names specified in shortOptSpec and longOptSpec (sans the = or : signs after them), if they were given on the command line, and the values they were given, if specified to take a value (using the = or : suffix).

Option Spec Format

Options to OptMain and ScalaGetOpt are specified as follows:

• short options: one String with one-character options, followed by : or = if the options take an argument. Example: "ac:df:g" tells ScalaGetOpt that your program accepts these options: -a -carg -d -f file.txt -g, where -c and -f must be given a positional argument ("arg" and "file.txt" in the example).

• long options: Seq[String] with each String specifying one option, followed by : or = if the option takes an argument. Example: Seq("archive", "compress=", "daemon", "file=", "global") tells ScalaGetOpt that your program accepts these options: --archive --compress=arg --daemon --file file.txt --global, where --compress and --file must be given a positional argument ("arg" and "file.txt" in the example).

• You are free to give the options in any order, both on the command line and in the option specs.

Scala REPL usage example

scala> import fi.helsinki.cs.nodes.util.ScalaGetOpt._
import fi.helsinki.cs.nodes.util.ScalaGetOpt._

scala> val args = Array("abcd", "-c", "--stuff", "stuffval")
args: Array[String] = Array(abcd, -c, --stuff, stuffval)

// Note that the "abcd" non-option is ignored here
scala> val options = getOpt(args, "c", Seq("stuff="))
options: scala.collection.immutable.Map[String,String] = Map(c -> "", stuff -> stuffval)

scala> val args = Array("abcd", "-c", "--stuff=stuffval")
args: Array[String] = Array(abcd, -c, --stuff=stuffval)

// You can specify values using --stuff=stuffval as well as --stuff stuffval
scala> val options = getOpt(args, "c", Seq("stuff="))
options: scala.collection.immutable.Map[String,String] = Map(c -> "", stuff -> stuffval)