Added ??? and NotImplementedError because this ...

Added ??? and NotImplementedError because this seemed to be the
opinion of the majority on the "Adding ??? to Predef?" thread on
scala-internals. No review.

2 files changed, 24 insertions, 0 deletions

diff --git a/src/library/scala/NotImplementedError.scala b/src/library/scala/NotImplementedError.scala
new file mode 100644
index 0000000000..393f4061a6
--- /dev/null
+++ b/src/library/scala/NotImplementedError.scala
@@ -0,0 +1,19 @@
+/*                     __                                               *\
+**     ________ ___   / /  ___     Scala API                            **
+**    / __/ __// _ | / /  / _ |    (c) 2002-2011, LAMP/EPFL             **
+**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
+** /____/\___/_/ |_/____/_/ | |                                         **
+**                          |/                                          **
+\*                                                                      */
+
+
+
+package scala
+
+/** Throwing this exception can be a temporary replacement for a method
+ *  body that remains to be implemented. For instance, the exception is thrown by
+ *  `Predef.???`.
+ */
+final class NotImplementedError(msg: String) extends Error(msg) {
+  def this() = this("an implementation is missing")
+}
diff --git a/src/library/scala/Predef.scala b/src/library/scala/Predef.scala
index 54111dceba..27197364c9 100644
--- a/src/library/scala/Predef.scala
+++ b/src/library/scala/Predef.scala
@@ -222,6 +222,11 @@ object Predef extends LowPriorityImplicits {
   }
   implicit def any2Ensuring[A](x: A): Ensuring[A] = new Ensuring(x)
 
+  /** `???` can be used for marking methods that remain to be implemented.
+   *  @throws  A `NotImplementedError`
+   */
+  def ??? : Nothing = throw new NotImplementedError
+
   // tupling ------------------------------------------------------------
 
   type Pair[+A, +B] = Tuple2[A, B]