Call asyncEnd only on success.

Call asyncEnd only on success.

BUG=
R=ahe@google.com, kustermann@google.com

Committed: https://code.google.com/p/dart/source/detail?r=27465

[kustermann, 2013-09-09 12:41:54]

lgtm, but let peter take a look as well.

https://codereview.chromium.org/23512008/diff/1/pkg/async_helper/lib/async_he...
File pkg/async_helper/lib/async_helper.dart (right):

https://codereview.chromium.org/23512008/diff/1/pkg/async_helper/lib/async_he...
pkg/async_helper/lib/async_helper.dart:65: }
In general I've noticed that people misuse these two methods sometimes. This
test for example is broken
main() {
  asyncStart();
  Timer.run(() { print("A"); asyncEnd(); });
  asyncStart();
  Timer.run(() { print("B"); asyncEnd(); });
}

It could be the case that the first closure was called twice (i.e. the result is
"AA") and the test would pass.

Maybe we should provide a convenience wrapper around asyncStart/asyncEnd, like
this:
main() {
  var asyncEndFn1 = asyncBegin();
  Timer.run(() { print("A"); asyncEndFn1(); });
  var asyncEndFn2 = asyncBegin();
  Timer.run(() { print("B"); asyncEndFn2(); });
}

So returning a closure which makes sure that it's only called once.

https://codereview.chromium.org/23512008/diff/1/pkg/async_helper/lib/async_he...
pkg/async_helper/lib/async_helper.dart:86: void asyncTest(f()) {
Either document this on the top of the file or at the method level. be
consistent (i.e. remove the comments on the top or add sections for these
methods as well).

[ahe, 2013-09-10 09:14:24]

LGTM.

This is my vision of the future:

asyncSuccess becomes a private method.

asyncEnd is deleted.

asyncStart returns an instance of a class, say PendingAsyncAction:

class PendingAsyncAction {
  void done();
}

asyncTest takes a future, not a function returning a future.

[Johnni Winther, 2013-09-13 07:34:59]

https://codereview.chromium.org/23512008/diff/1/pkg/async_helper/lib/async_he...
File pkg/async_helper/lib/async_helper.dart (right):

https://codereview.chromium.org/23512008/diff/1/pkg/async_helper/lib/async_he...
pkg/async_helper/lib/async_helper.dart:86: void asyncTest(f()) {
On 2013/09/09 12:41:54, kustermann wrote:
> Either document this on the top of the file or at the method level. be
> consistent (i.e. remove the comments on the top or add sections for these
> methods as well).

Added a top comment as well.

[Johnni Winther, 2013-09-13 07:36:59]

Committed patchset #3 manually as r27465 (presubmit successful).