在Scala中解析命令行参数的最佳方法是什么? 我个人更喜欢一些不需要外部罐子的轻量级的东西。

相关:

我如何解析Java中的命令行参数? c++有哪些参数解析器库? 在c#中解析命令行参数的最佳方法


当前回答

还有JCommander(免责声明:我创建了它):

object Main {
  object Args {
    @Parameter(
      names = Array("-f", "--file"),
      description = "File to load. Can be specified multiple times.")
    var file: java.util.List[String] = null
  }

  def main(args: Array[String]): Unit = {
    new JCommander(Args, args.toArray: _*)
    for (filename <- Args.file) {
      val f = new File(filename)
      printf("file: %s\n", f.getName)
    }
  }
}

其他回答

因为每个人都发布了自己的解决方案,这里是我的,因为我想为用户写一些更简单的东西:https://gist.github.com/gwenzek/78355526e476e08bb34d

要点包含一个代码文件,一个测试文件和一个简短的示例复制在这里:

import ***.ArgsOps._


object Example {
    val parser = ArgsOpsParser("--someInt|-i" -> 4, "--someFlag|-f", "--someWord" -> "hello")

    def main(args: Array[String]){
        val argsOps = parser <<| args
        val someInt : Int = argsOps("--someInt")
        val someFlag : Boolean = argsOps("--someFlag")
        val someWord : String = argsOps("--someWord")
        val otherArgs = argsOps.args

        foo(someWord, someInt, someFlag)
    }
}

没有什么特别的选项可以强制变量在某些边界内,因为我觉得解析器不是这样做的最佳场所。

注意:对于一个给定的变量,你可以有任意多的别名。

我喜欢这段代码的简洁外观…从这里的讨论中收集到: http://www.scala-lang.org/old/node/4380

object ArgParser {
  val usage = """
Usage: parser [-v] [-f file] [-s sopt] ...
Where: -v   Run verbosely
       -f F Set input file to F
       -s S Set Show option to S
"""

  var filename: String = ""
  var showme: String = ""
  var debug: Boolean = false
  val unknown = "(^-[^\\s])".r

  val pf: PartialFunction[List[String], List[String]] = {
    case "-v" :: tail => debug = true; tail
    case "-f" :: (arg: String) :: tail => filename = arg; tail
    case "-s" :: (arg: String) :: tail => showme = arg; tail
    case unknown(bad) :: tail => die("unknown argument " + bad + "\n" + usage)
  }

  def main(args: Array[String]) {
    // if there are required args:
    if (args.length == 0) die()
    val arglist = args.toList
    val remainingopts = parseArgs(arglist,pf)

    println("debug=" + debug)
    println("showme=" + showme)
    println("filename=" + filename)
    println("remainingopts=" + remainingopts)
  }

  def parseArgs(args: List[String], pf: PartialFunction[List[String], List[String]]): List[String] = args match {
    case Nil => Nil
    case _ => if (pf isDefinedAt args) parseArgs(pf(args),pf) else args.head :: parseArgs(args.tail,pf)
  }

  def die(msg: String = usage) = {
    println(msg)
    sys.exit(1)
  }

}

我喜欢joslinm的slide()方法,而不是可变的vars;)这里有一个不可改变的方法:

case class AppArgs(
              seed1: String,
              seed2: String,
              ip: String,
              port: Int
              )
object AppArgs {
  def empty = new AppArgs("", "", "", 0)
}

val args = Array[String](
  "--seed1", "akka.tcp://seed1",
  "--seed2", "akka.tcp://seed2",
  "--nodeip", "192.167.1.1",
  "--nodeport", "2551"
)

val argsInstance = args.sliding(2, 1).toList.foldLeft(AppArgs.empty) { case (accumArgs, currArgs) => currArgs match {
    case Array("--seed1", seed1) => accumArgs.copy(seed1 = seed1)
    case Array("--seed2", seed2) => accumArgs.copy(seed2 = seed2)
    case Array("--nodeip", ip) => accumArgs.copy(ip = ip)
    case Array("--nodeport", port) => accumArgs.copy(port = port.toInt)
    case unknownArg => accumArgs // Do whatever you want for this case
  }
}

我的方法基于上面的答案(来自dave4420),并试图通过使其更通用来改进它。

它返回所有命令行参数的映射[String,String] 你可以查询你想要的特定参数(例如使用.contains)或将值转换为你想要的类型(例如使用toInt)。

def argsToOptionMap(args:Array[String]):Map[String,String]= {
  def nextOption(
      argList:List[String], 
      map:Map[String, String]
    ) : Map[String, String] = {
    val pattern       = "--(\\w+)".r // Selects Arg from --Arg
    val patternSwitch = "-(\\w+)".r  // Selects Arg from -Arg
    argList match {
      case Nil => map
      case pattern(opt)       :: value  :: tail => nextOption( tail, map ++ Map(opt->value) )
      case patternSwitch(opt) :: tail => nextOption( tail, map ++ Map(opt->null) )
      case string             :: Nil  => map ++ Map(string->null)
      case option             :: tail => {
        println("Unknown option:"+option) 
        sys.exit(1)
      }
    }
  }
  nextOption(args.toList,Map())
}

例子:

val args=Array("--testing1","testing1","-a","-b","--c","d","test2")
argsToOptionMap( args  )

给:

res0: Map[String,String] = Map(testing1 -> testing1, a -> null, b -> null, c -> d, test2 -> null)

还有JCommander(免责声明:我创建了它):

object Main {
  object Args {
    @Parameter(
      names = Array("-f", "--file"),
      description = "File to load. Can be specified multiple times.")
    var file: java.util.List[String] = null
  }

  def main(args: Array[String]): Unit = {
    new JCommander(Args, args.toArray: _*)
    for (filename <- Args.file) {
      val f = new File(filename)
      printf("file: %s\n", f.getName)
    }
  }
}