This post originated from an RSS feed registered with Scala Buzz by Zemian Deng. Original Post: Parsing simple command line options in Scala Feed Title: thebugslayer Feed URL: http://www.jroller.com/thebugslayer/feed/entries/atom?cat=%2FScala+Programming Feed Description: Notes on Scala and Sweet web framework Latest Scala Buzz Posts Latest Scala Buzz Posts by Zemian Deng Latest Posts From thebugslayer

I noticed there is an example from Scala site on using match to parse the command line options. I wondered if there is better way to do this without making the "verbose" variable mutable.

After looking around on the Scala API, I noticed the "partition" method in Iterable class could be useful in this case. Here is my attempt to parse some simple command line options apart from arguments inputs. I will assume all options can start with "-" or "--", and if there is optional-parameter, it must use "=" in between without space.

//file: test.scala



//seperate options from argumetns

val (opts, args) = argv.partition{ _.startsWith("-") }


//turning options array into map

val optsMap = Map() ++ opts.map{ x => 

  val pair = x.split("-{1,2}")(1).split("=")

  if(pair.length ==1) (pair(0), "true") else (pair(0), pair(1))

}     


//use the option values

val verbose = optsMap.getOrElse("v", "false").toBoolean

val number = optsMap.getOrElse("n", "0").toInt


if(verbose)

  println("program started")


println("number used in program is " + number)

println("program arguments count is " + args.length)

Testing:

oolarcher07:scala thebugslayer$ scala test.scala

number used in program is 0

program arguments count is 0

coolarcher07:scala thebugslayer$ scala test.scala -v

program started

number used in program is 0

program arguments count is 0

coolarcher07:scala thebugslayer$ scala test.scala -v 1 2 3

program started

number used in program is 0

program arguments count is 3

coolarcher07:scala thebugslayer$ scala test.scala -v 1 2 3 -n=55

program started

number used in program is 55

program arguments count is 3

coolarcher07:scala thebugslayer$ scala test.scala -v 1 2 3 --n=55

program started

number used in program is 55

program arguments count is 3

If you know any other interesting ways, please share.