Question

请提供一个代码示例，说明如何以编程方式创建嵌入式Scala REPL解释器，该解释器适用于Scala 2.10。 （我花了几个小时梳理各种代码片段以获得一名有效的口译员后，我添加了这个Q＆amp; A）

Answer 1

示例Repl.scala：

import scala.tools.nsc.interpreter._
import scala.tools.nsc.Settings


object Repl extends App {
  def repl = new ILoop {
    override def loop(): Unit = {
      intp.bind("e", "Double", 2.71828)
      super.loop()
    }
  }

  val settings = new Settings
  settings.Yreplsync.value = true


  //use when launching normally outside SBT
  settings.usejavacp.value = true      

  //an alternative to 'usejavacp' setting, when launching from within SBT
  //settings.embeddedDefaults[Repl.type]

  repl.process(settings)
}

一些注释

我选择显示JLineReader（默认）而不是SimpleReader，因为它工作得更好，正确处理箭头键，删除等.JLine确实添加了jar依赖。
该示例显示了如何将值绑定到repl（上面的变量e）。
当我省略settings.Yreplsync.value = true时，REPL挂起并且没用。
根据我的测试，如果将usejavacp和embeddedDefaults设置组合在一起，则会出现错误结果

我觉得最容易通过SBT进行测试;样本build.sbt：

name := "Repl"

organization := "ExamplesRUs"

scalaVersion := "2.10.2"

libraryDependencies ++= Seq(
 "org.scala-lang" % "scala-compiler" % "2.10.2",
 "org.scala-lang" % "jline" % "2.10.2"
)

样本SBT会话：

> run-main Repl
[info] Running Repl
Welcome to Scala version 2.10.2 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_37).
Type in expressions to have them evaluated.
Type :help for more information.
e: Double = 2.71828

scala> 2 * e
res1: Double = 5.43656

scala>

Answer 2

基于Ben的优秀答案，下面是一个帮助类来轻松启动解释器。用法：

Repl.run(("e", "Double", 2.71828), ("pi", "Double", 3.1415))

它会自动检测您何时从SBT运行并适应。

Repl.scala：

import scala.tools.nsc.interpreter.ILoop
import scala.tools.nsc.Settings
import java.io.CharArrayWriter
import java.io.PrintWriter

object Repl {

  def run(params: (String, String, Any)*) {

    def repl = new ILoop {
      override def loop(): Unit = {
        params.foreach(p => intp.bind(p._1, p._2, p._3))
        super.loop()
      }
    }

    val settings = new Settings
    settings.Yreplsync.value = true

    // Different settings needed when running from SBT or normally
    if (isRunFromSBT) {
      settings.embeddedDefaults[Repl.type]
    } else {
      settings.usejavacp.value = true
    }

    repl.process(settings)
  }

  def isRunFromSBT = {
    val c = new CharArrayWriter()
    new Exception().printStackTrace(new PrintWriter(c))
    c.toString().contains("at sbt.")
  }

}

2.10的嵌入式Scala REPL解释器示例

2 个答案: