Fix Promise#filter

[julienrf]

#459

• Fix Promise#filter so it never leads to an unredeemable promise ;
• Follow the Scala standard Future#filter behavior when the predicate fails: throw a NoSuchElementException ;
• Remove STMPromise#collect which was wrong and anyway not expose at the Promise interface level.

[pk11]

Hi @sadache, it looks OK to me but could you please check this?

[sadache]

Yes, Ok for me too. But the pull request needs to be cleaned from the two other unrelated commits. This means we integrate only 9d69b11.
Thanks Julien for this fix.

[sadache]

Actually not so sure any more.
Maybe leaving filter as is and making collect public is better.
The idea is that you can combine two or more filtered promises using "or".

[julienrf]

So you want to leave the filter implementation as is (silently blocking? See the related ticket on the tracker)? This implementation is different than the one in scala 2.10. The same applies for collect.

On 21 mai 2012, at 20:02, Sadek Drobi reply@reply.github.com wrote:

Actually not so sure any more.
Maybe leaving filter as is and making collect public is better.
The idea is that you can combine two or more filtered promises using "or".

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#302 (comment)

[sadache]

Nothing is blocking, but it never redeems.
I want to find a way to keep the very interesting and practical functionality to "or" different potentially redeeming promises.

[sadache]

clean the pull request so that I can pull it before I change my mind

[julienrf]

Ok, I understand your points. There is a Future#either which seems to perform the Promise#or of Play, unless I’m wrong?

[julienrf]

Implementation is here: https://github.com/scala/scala/blob/master/src/library/scala/concurrent/Future.scala#L524

[sadache]

The Future#either would return NoSuchElement if the first redeemed future is out of the filter (whereas the second could be satisfactory)

[julienrf]

Oh yes, you’re right… We could write a orSuccess which would perform what you said?

[sadache]

Won't work, I want to use error in worst case scenario (both promises return an error), ignoring NoSuchElement is wrong because it could happen from something else.