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simple scala command line options parsing

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scopt is a little command line options parsing library.

Its based on the code from Tim Perrett which his based on Aaron Harnly's code mentioned in this thread and this thread which is available as a gist or here.


libraryDependencies += "com.github.scopt" %% "scopt" % "2.0.0"


Create an OptionParser and customise it with the options you need, passing in functions to process each option or argument.

val parser = new OptionParser("scopt", "1.x") {
  intOpt("f", "foo", "foo is an integer property", {v: Int => = v})
  opt("o", "output", "<file>", "output is a string property", {v: String => = v})
  booleanOpt("xyz", "xyz is a boolean property", {v: Boolean => = v})
  keyValueOpt("l", "lib", "<libname>", "<filename>", "load library <libname>",
    {(key: String, value: String) => { config.libname = key; config.libfile = value } })
  arg("<singlefile>", "<singlefile> is an argument", {v: String => config.whatnot = v})
  // arglist("<file>...", "arglist allows variable number of arguments",
  //   {v: String => config.files = (v :: config.files).reverse })
if (parser.parse(args)) {
  // do stuff
else {
  // arguments are bad, usage message will have been displayed

The above generates the following usage text:

Usage: scopt [options] <filename>

  -f <value> | --foo <value>
        foo is an integer property
  -o <file> | --output <file>
        output is a string property
  --xyz <value>
        xyz is a boolean property
  -l:<libname>=<filename> | --lib:<libname>=<filename>
        load library <libname>
        <singlefile> is an argument

Immutable Parser

scopt now provides immutable parser:

val parser = new scopt.immutable.OptionParser[Config]("scopt", "2.x") { def options = Seq(
  intOpt("f", "foo", "foo is an integer property") { (v: Int, c: Config) => c.copy(foo = v) },
  opt("o", "output", "output") { (v: String, c: Config) => c.copy(bar = v) },
  booleanOpt("xyz", "xyz is a boolean property") { (v: Boolean, c: Config) => c.copy(xyz = v) },
  keyValueOpt("l", "lib", "<libname>", "<filename>", "load library <libname>")
    { (key: String, value: String, c: Config) => c.copy(libname = key, libfile = value) },
  keyIntValueOpt(None, "max", "<libname>", "<max>", "maximum count for <libname>")
    { (key: String, value: Int, c: Config) => c.copy(maxlibname = key, maxcount = value) },
  arg("<file>", "some argument") { (v: String, c: Config) => c.copy(whatnot = v) }
) }
// parser.parse returns Option[C]
parser.parse(args, Config()) map { config =>
  // do stuff
} getOrElse {
  // arguments are bad, usage message will have been displayed


sbt to build scopt.


MIT License.


See notes.

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