Restored the stack traces I'd accidentally smot...

Restored the stack traces I'd accidentally smothered in r23426, and
cleaned up ObjectRunner/ScriptRunner a bit. Closes #3978, no review.

1 files changed, 14 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/ObjectRunner.scala b/src/compiler/scala/tools/nsc/ObjectRunner.scala
index f2ddc84445..987a6b0ba0 100644
--- a/src/compiler/scala/tools/nsc/ObjectRunner.scala
+++ b/src/compiler/scala/tools/nsc/ObjectRunner.scala
@@ -8,6 +8,7 @@ package scala.tools.nsc
 
 import java.net.URL
 import util.ScalaClassLoader
+import java.lang.reflect.InvocationTargetException
 
 /** An object that runs another object specified by name.
  *
@@ -24,10 +25,22 @@ object ObjectRunner {
    *  specified classpath and argument list.
    *
    *  @throws ClassNotFoundException
-   *  @throws NoSuchMethodError
+   *  @throws NoSuchMethodException
    *  @throws InvocationTargetException
    */
   def run(urls: List[URL], objectName: String, arguments: Seq[String]) {
     (ScalaClassLoader fromURLs urls).run(objectName, arguments)
   }
+
+  /** Catches exceptions enumerated by run (in the case of InvocationTargetException,
+   *  unwrapping it) and returns it any thrown in Left(x).
+   */
+  def runAndCatch(urls: List[URL], objectName: String, arguments: Seq[String]): Either[Throwable, Unit] = {
+    try Right(run(urls, objectName, arguments))
+    catch {
+      case e: ClassNotFoundException    => Left(e)
+      case e: NoSuchMethodException     => Left(e)
+      case e: InvocationTargetException => Left(e.getCause match { case null => e ; case cause => cause })
+    }
+  }
 }