Scala example source code file (Demo.scala)

This example Scala source code file (Demo.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Scala tags/keywords

demo, demospec, demospec, instance, int, int, list, list, property, spec, speccommandline, string, string, usage

The Scala Demo.scala source code

/* NEST (New Scala Test)
 * Copyright 2007-2011 LAMP/EPFL
 * @author  Paul Phillips
 */

package scala.tools
package cmd

/** A sample command specification for illustrative purposes.
 *  First take advantage of the meta-options:
 *  
 *    // this command creates an executable runner script "demo"
 *    % scala scala.tools.cmd.Demo --self-update demo
 *
 *    // this one creates and sources a completion file - note backticks
 *    % `./demo --bash`
 *
 *    // and now you have a runner with working completion
 *    % ./demo --<tab>
 *       --action           --defint           --int
 *       --bash             --defstr           --str
 *       --defenv           --self-update      --unary
 *
 *  The normal option configuration is plausibly self-explanatory.
 */
trait DemoSpec extends Spec with Meta.StdOpts with Interpolation {
  lazy val referenceSpec  = DemoSpec
  lazy val programInfo    = Spec.Info("demo", "Usage: demo [<options>]", "scala.tools.cmd.Demo")

  help("""Usage: demo [<options>]""")
  heading("Unary options:")

  val optIsUnary      = "unary"         / "a unary option"              --?  ;
  ("action" / "a body which may be run") --> println("Hello, I am the --action body.")
  
  heading("Binary options:")
  val optopt          = "str"       / "an optional String"        --|
  val optoptInt       = ("int"      / "an optional Int") .        --^[Int]
  val optEnv          = "defenv"    / "an optional String"        defaultToEnv  "PATH"
  val optDefault      = "defstr"    / "an optional String"        defaultTo     "default"
  val optDefaultInt   = "defint"    / "an optional Int"           defaultTo     -1
  val optExpand       = "alias"     / "an option which expands"   expandTo      ("--int", "15")
}

object DemoSpec extends DemoSpec with Property {
  lazy val propMapper = new PropertyMapper(DemoSpec)

  type ThisCommandLine = SpecCommandLine
  def creator(args: List[String]) =
    new SpecCommandLine(args) {
      override def errorFn(msg: String) = { println("Error: " + msg) ; sys.exit(0) }
    }
}

class Demo(args: List[String]) extends {
  val parsed = DemoSpec(args: _*)
} with DemoSpec with Instance {
  import java.lang.reflect._

  def helpMsg = DemoSpec.helpMsg
  def demoSpecMethods = this.getClass.getMethods.toList
  private def isDemo(m: Method) = (m.getName startsWith "opt") && !(m.getName contains "$") && (m.getParameterTypes.isEmpty)  

  def demoString(ms: List[Method]) = {
    val longest   = ms map (_.getName.length) max
    val formatStr = "    %-" + longest + "s: %s"
    val xs        = ms map (m => formatStr.format(m.getName, m.invoke(this)))
    
    xs mkString ("Demo(\n  ", "\n  ", "\n)\n")
  }
    
  override def toString = demoString(demoSpecMethods filter isDemo)
}

object Demo {
  def main(args: Array[String]): Unit = {
    val runner = new Demo(args.toList)

    if (args.isEmpty)
      println(runner.helpMsg)
    
    println(runner)
  }
}