Handle an exception handler returning null more gracefully.

corelib/src/implementation/future_implementation.dart

-// Copyright 2011 Google Inc. All Rights Reserved.
+// Copyright 2012 Google Inc. All Rights Reserved.
 // Dart core library.
 
 class FutureImpl<T> implements Future<T> {
 
-  bool _isComplete;
+  bool _isComplete = false;
 
   /**
    * Value that was provided to this Future by the Completer
    */
   T _value;
 
   /**
    * Exception that occured, if there was a problem providing
    * Value.
    */
   Object _exception;
 
   /**
    * true, if any onException handler handled the exception.
    */
-  bool _exceptionHandled;
+  bool _exceptionHandled = false;

[Siggi Cherem (dart-lang), 2012/04/27 22:32:51]

yay!

 
   /**
    * Listeners waiting to receive the value of this future.
    */
   final List<Function> _listeners;
 
   /**
    * Exception handlers waiting for exceptions.
    */
   final List<Function> _exceptionHandlers;
 
-  FutureImpl() : _listeners = new List(), _exceptionHandlers = new List() {
-    _isComplete = false;
-    _exceptionHandled = false;
-  }
+  FutureImpl()
+    : _listeners = [],
+      _exceptionHandlers = [];
 
   factory FutureImpl.immediate(T value) {
     final res = new FutureImpl();
     res._setValue(value);
     return res;
   }
 
   T get value() {
     if (!isComplete) {
       throw new FutureNotCompleteException();
@@ skipping 37 matching lines @@
        }
     } else {
       _exceptionHandlers.add(onException);
     }
   }
 
   void _complete() {
     _isComplete = true;
     if (_exception !== null) {
       for (Function handler in _exceptionHandlers) {
-        if (handler(_exception)) {
+        // Explicitly check for true here so that if the handler returns null,

[Siggi Cherem (dart-lang), 2012/04/27 22:32:51]

booo! :(

+        // we don't get an exception in checked mode.
+        if (handler(_exception) == true) {
           _exceptionHandled = true;
           break;
         }
       }
     }
+
     if (hasValue) {
       for (Function listener in _listeners) {
         listener(value);
       }
     } else {
       if (!_exceptionHandled && _listeners.length > 0) {
         throw _exception;
       }
     }
   }
@@ skipping 72 matching lines @@
   }
 
   void complete(T value) {
     _futureImpl._setValue(value);
   }
 
   void completeException(var exception) {
     _futureImpl._setException(exception);
   }
 }