Docserver: Update Future.Then() to be more Promise-like

Docserver: Update Future.Then() to be more Promise-like

BUG=306341
NOTRY=True

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287482

[ahernandez, 2014-07-31 19:39:27]

This is the next patch in a series of CLs converting the def resolve() pattern
to the Future.Then() pattern. I also modified the functionality of Future.Then()
to be more Promise-like. PTAL.

[Yoyo Zhou, 2014-08-01 22:03:19]

https://chromiumcodereview.appspot.com/417163004/diff/20001/chrome/common/ext...
File chrome/common/extensions/docs/server2/future.py (right):

https://chromiumcodereview.appspot.com/417163004/diff/20001/chrome/common/ext...
chrome/common/extensions/docs/server2/future.py:68: def Then(self, callback,
error_handler=_DefaultErrorHandler):
This should come with tests.

P.S. You should make changes like this separate from the other changes, since
they don't inherently have anything to do with each other. (It would be
different if some of them used this.)

https://chromiumcodereview.appspot.com/417163004/diff/20001/chrome/common/ext...
chrome/common/extensions/docs/server2/future.py:74: return callback(self.Get())
If I'm reading the Promise description correctly, it seems like the try/except
here should only cover self.Get. Otherwise, if you have a chain of callbacks,
and one of the later one throws an exception, it gets caught, and only the first
one's error handler gets called. But feel free to enlighten me on what the
correct behavior should be.

[ahernandez, 2014-08-04 18:51:19]

I added tests and modified the Then() logic, PTAL.

https://chromiumcodereview.appspot.com/417163004/diff/20001/chrome/common/ext...
File chrome/common/extensions/docs/server2/future.py (right):

https://chromiumcodereview.appspot.com/417163004/diff/20001/chrome/common/ext...
chrome/common/extensions/docs/server2/future.py:68: def Then(self, callback,
error_handler=_DefaultErrorHandler):
On 2014/08/01 22:03:19, Yoyo Zhou wrote:
> This should come with tests.
> 
> P.S. You should make changes like this separate from the other changes, since
> they don't inherently have anything to do with each other. (It would be
> different if some of them used this.)

The other changes do use the new changes from future.py (see file_system.py for
example).

[Yoyo Zhou, 2014-08-04 23:22:18]

LGTM

[ahernandez, 2014-08-04 23:47:30]

The CQ bit was checked by ahernandez.miralles@gmail.com

[commit-bot: I haz the power, 2014-08-04 23:48:49]

CQ is trying da patch. Follow status at

https://chromium-status.appspot.com/cq/ahernandez.miralles@gmail.com/41716300...

[commit-bot: I haz the power, 2014-08-05 07:46:11]

Change committed as 287482