scala0.cmdline
DESCRIPTION
Boston Area Scala Enthusiasts second meeting held on Dec 2, 2009.Talk delivered by Jeremy Cloud.TRANSCRIPT
jeremy.cloud {• ~2 years professional development
with Scala
• freelance software developer / web designer -- hire me!
}
Friday, December 4, 2009
Friday, December 4, 2009
scala0.cmdline:
• distinct command-line modes
• support complex dependencies between options
• validation using typed failures so you can customize error messages
• generates nicely formatted usage message
• short and/or long names
• dependency free
Friday, December 4, 2009
distinct command-line modes
foo -vfoo -?foo -c [-f num] filenames...foo [-d dir] [-l limit] filename
command-line parser will tell you whichvariation is being used
Friday, December 4, 2009
dependencies between options
if a then b: foo [-a blah -b bleh]
arbitrarily nested: foo [-a (-b | -c -d)]
one of a, b, c: foo (-a blah | -b bleh | -c)
b only if a: foo [-a blah [-b bleh]]
Friday, December 4, 2009
uses internal DSL
object Options extends CommandLineParser { val version = Flag("v", "version", "Print version and quit") val help = Flag("?", "help", "Print help and quit") val a = Flag("a", None, "A") val b = Flag("b", None, "B") val c = Flag("c", None, "C") val d = Flag("d", None, "D") val filename = NakedArgument("filename", "The name of the file") val versionMode = %(version) val helpMode = %(help) val defaultMode = %((a ~ (b | c ~ d)).?, filename) val spec = %%(versionMode, helpMode, defaultMode)}
Friday, December 4, 2009
mode and error matching
def main(args: Array[String]) { Options(args) match { case Left(error) => Console.err.println(error) Options.printHelp("foo")
case Right((Options.versionMode, _)) => Console.out.println("Version 1.0")
case Right((Options.helpMode, _)) => Options.printHelp("foo")
case Right((Options.defaultMode, cmdLine)) => val isA = cmdLine(Options.a) val filename = cmdLine(Options.filename).head // do something... }}
Friday, December 4, 2009
generates nice help messages
USAGE: foo -v foo -? foo [-a (-b | -c -d)] filename
OPTIONS: -?, --help Print help and quit -a, --accelerator enable accelerator -b, --blaster use blaster -c, --cool make it cool -d, --dump dumb it down -v, --version Print version and quit
Friday, December 4, 2009
