Handle Future result from Future.sync computation

sdk/lib/async/future.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.async;
 
 /**
  * An object representing a delayed computation.
  *
  * A [Future] is used to obtain a not yet
@@ skipping 110 matching lines @@
    * error. If a thrown value is an [AsyncError], it is used
    * directly, instead of wrapping this error again in another [AsyncError].
    *
    * If the returned value is itself a [Future], completion of
    * the created future will wait until the returned future completes,
    * and will then complete with the same result.
    */
   factory Future.sync(computation()) {
     try {
       var result = computation();
-      return new Future<T>.value(result);
+      return new Future.value(result);

[kevmoo-old, 2013/09/17 17:21:41]

After I did the update, I decided I don't like this either.

[floitsch, 2013/09/17 17:59:44]

This Future<T> is correct. But the Future.value should not expect a T.
It means that the value will not be type-checked immediately but it will be
checked eventually (and we can help it by assigning it to T after the Future
check).

     } catch (error, stackTrace) {
       return new Future<T>.error(error, stackTrace);
     }
   }
 
   /**
    * A future whose value is available in the next event-loop iteration.
    *
    * If [value] is not a [Future], using this constructor is equivalent
    * to [:new Future.sync(() => value):].
@@ skipping 216 matching lines @@
    */
   Stream<T> asStream();
 }
 
 /**
  * A way to produce Future objects and to complete them later
  * with a value or error.
  *
  * If you already have a Future, you probably don't need a Completer.
  * Instead, you can usually use [Future.then], which returns a Future:
- * 
+ *
  *     Future doStuff(){
  *       return someAsyncOperation().then((result) {
  *         // Do something.
  *       });
  *     }
  *
  * If you do need to create a Future from scratch—for example,
  * when you're converting a callback-based API into a Future-based
  * one—you can use a Completer as follows:
  *
@@ skipping 86 matching lines @@
    *
    * The argument [exception] must not be `null`.
    */
   void completeError(Object exception, [Object stackTrace]);
 
   /**
    * Whether the future has been completed.
    */
   bool get isCompleted;
 }