Global.Run NullPointerException

Hi.

After digging a bit into the source code of the IMain class, I noticed
that the NullPointerException is triggered because to access the Run
constructor, you need to already have the englobing Global class
instantiated in the IMain.global lazy val.

In my case, IMain.global is evaluated to null, which means that the
following code fails to initialise properly the IMain.global val.

/** the public, go through the future compiler */
lazy val global: Global = {
if (isInitializeComplete) _compiler
else {
// If init hasn't been called yet you're on your own.
if (_isInitialized == null) {
repldbg("Warning: compiler accessed before init set up. Assuming no postInit code.")
initialize(())
}
// blocks until it is ; false means catastrophic failure
if (_isInitialized()) _compiler
else null /* Execution ends up getting there */
}
}

How do I make sure that the IMain.global value is properly initialised?

Le Thursday 16 Feb 2012 à 09:30:05 (+0100), Guillaume Yziquel a écrit :
> Hi.
>
> I'm trying to use the scala.tools.nsc.interpreter.IMain class within an
> OSGi framework, and am stumbling on the following stack trace (using
> scala 2.9.1):
>
> Caused by: java.lang.NullPointerException
> at scala.tools.nsc.Global$Run.(Global.scala:663)
> at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compileAndSaveRun(IMain.scala:755)
> at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.compile(IMain.scala:731)
> at scala.tools.nsc.interpreter.IMain.bind(IMain.scala:591)
> at scala.tools.nsc.interpreter.IMain.bind(IMain.scala:626)
>
> which is triggered by code like that:
>
> val mapping : Array[String] => (F, L) = {
>
> val code : String = {
> val path = "myCode.scala"
> var code : String = null
> def resource = this.getClass.getClassLoader.getResourceAsStream(_)
> val source = scala.io.Source.fromInputStream (resource (path))
> source.withClose(() => code = source.mkString); code
> }
>
> import scala.tools.nsc._
> val settings = new Settings; settings.usejavacp.value = true
> val interp = new interpreter.IMain (settings) {
> interp =>
>
> def execute (code : String) : Array[String] => (F, L) = {
>
> val result = new Array[Array[String] => (F, L)](1)
> /* Blows up on the following line: */
> interp.bind(interpreter.NamedParam("res", "Array[Array[String] => (F, L)]", result))
>
> interp.interpret(code)
>
> result(0)
> }
>
> }
>
> While this kind of code works almost fine in the REPL, it blows up when
> deployed in an OSGi bundle. As it is a constructor of Global.Run that
> fails, it looks like I have failed to initialise it properly. Would very
> much like to know where the 2.9.1 version of scala.tools.nsc is
> documented in detail.