How to use scalax.io.CommandLineParser?

Question

I want to create a class that takes a string array as a constructor argument and has command line parameter values ​​as vals members. Something like below, but I don't understand how Bistate works.

import scalax.data._
import scalax.io.CommandLineParser

class TestCLI(arguments: Array[String]) extends CommandLineParser {
    private val opt1Option = new Flag("p", "print") with AllowAll
    private val opt2Option = new Flag("o", "out") with AllowAll
    private val strOption = new StringOption("v", "value") with AllowAll
    private val result = parse(arguments)
    // true or false
    val opt1 = result(opt1Option)
    val opt2 = result(opt2Option)
    val str = result(strOption)
}

Answer 1

Below are shorter alternatives to this pattern to get a boolean:

val opt1 = result(opt1Option).isInstanceOf[Positive[_]]
val opt2 = result(opt2Option).posValue.isDefined

The second is probably better. The posValue field is an option (there is negValue ). The isDefined method of the option indicates whether it is Some (x) or None.

Answer 2

Scalax Bistate , , - . Scala (Either), , .

, Bistate Either Option, , "None -" . , Either, - :

def div(a: Int, b: Int) = if (b != 0) Left(a / b) else Right("Divide by zero")

div(4, 2) match {
  case Left(x) => println("Result: " + x)
  case Right(e) => Println("Error: " + e)
}

"Result: 2". Either . Left, , - , , Right.

Answer 3

So, if I want to assign a variable the boolean value of whether a flag is found, should I do as shown below?

val opt1 = result(opt1Option) match {
    case Positive(_) => true
    case Negative(_) => false
}

Is there no way to write this general case with less code than this?