Observable.sort method

[davidmoten]

I'd like to add Observable.sort (or Observable.sorted) to the API. I tried this a couple of years ago and it was knocked back but now that people are getting used to the offerings of java 8 streams for instance (and its .sorted() method) I thought I'd raise it again.

In particular to sort a stream at the moment I have to call

observable.toSortedList().flatMapIterable(x -> x)

or using an internal class:

observable.toSortedList().flatMapIterable(UtilityFunctions.<T>identity())

This is poor for discoverability, hard to read, and pretty disappointing when I want to show off RxJava's coolness.

Any takers?

[SherifMakhlouf]

@davidmoten would you forward the calls to corresponding toSortedList() like your example:
observable.toSortedList().flatMapIterable(UtilityFunctions.<T>identity()) ?
I'm curious if you would implement it differently

[davidmoten]

@SherifMakhlouf yes I'd forward the call because I think there are enough operators to support as is.

[davidmoten]

@SherifMakhlouf happy for you to run with PR. I was looking for support from committers before making one.

[SherifMakhlouf]

@davidmoten Thanks ! glad to support !

[abersnaze]

We may want to consider Observable<T> mergeSorted(Observable<Observable<T> sortedObservables, Func2<T, T, Integer> sortFunction) that takes a two or more already sorted observables and produces a new sorted observable with the results merged. It would work kind of like zip where is would wait for at least one onNext from each inner Observable<T> and only emit the smallest T.

[davidmoten]

@abersnaze yep I use that functionality and there is an operator for that orderedMergeWith in rxjava-extras. It was written by @akarnokd.

[akarnokd]

Closing via #4264.