Improvement on future: add stack trace to future failures.

lib/core/future.dart

Index: lib/core/future.dart
diff --git a/lib/core/future.dart b/lib/core/future.dart
index 99af2415180efcd019af18bce4ad6a7800ef087b..ea395491141149aced37fdb6ab0e4437d01a72e1 100644
--- a/lib/core/future.dart
+++ b/lib/core/future.dart
@@ -193,6 +193,22 @@ class FutureAlreadyCompleteException implements Exception {
   String toString() => "Exception: future already completed";
 }
 
+/**
+ * Wraps unhandled exceptions provided to [Completer.completeException]. It is
+ * used to show both the error message and the stack trace for unhandled
+ * exceptions.
+ */
+class FutureUnhandledException implements Exception {
+  /** Wrapped exception. */
+  var source;
+
+  /** Trace for the wrapped exception. */
+  var stackTrace;
+
+  FutureUnhandledException(this.source, this.stackTrace);

[Jennifer Messerly, 2012/10/19 23:54:15]

nit: newline after this

+  String toString() => "$source\n$stackTrace".replaceAll('\n','\n  ');

[Jennifer Messerly, 2012/10/19 23:54:15]

include more context here? maybe something like:

FutureUnhandledException: exception while executing Future:
  ${source.replaceAll('\n','\n  ')}
original stack trace:
  ${stackTrace.replaceAll('\n','\n  ')}

+}
+
 
 /**
  * [Futures] holds additional utility functions that operate on [Future]s (for