2.x: Add materialize() and dematerialize() #6278
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@@ Coverage Diff @@
## 2.x #6278 +/- ##
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- Coverage 98.25% 98.22% -0.03%
- Complexity 6259 6277 +18
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Files 667 672 +5
Lines 44887 44954 +67
Branches 6213 6216 +3
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+ Hits 44104 44158 +54
- Misses 247 258 +11
- Partials 536 538 +2
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| @CheckReturnValue | ||
| @SchedulerSupport(SchedulerSupport.NONE) | ||
| @Experimental | ||
| public final <T2> Maybe<T2> dematerialize() { |
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I find this API very awkward since it's available on every type but should only be used on Single<Notification<T>>. I don't have a better suggestion though. Except defining it yourself and using a Kotlin extension function.
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This has been the workaround for Observable.dematerialize too.
The alternative is to have the user select the notification:
Maybe<R> dematerialize(Function<T, Notification<R>> selector);
thus if you have a Single<Notification<T>>, you only need an identity selector:
Single<Notification<T>> source = ...
Maybe<T> source.dematerialize(v -> v);However, this selector pattern is not an established one in RxJava right now. We could go for this but then the other existing dematerialize operators should also get a selector overload.
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Didn't know about dematerialize, then I guess we stick to that convention. Providing a mapper sounds good. Then maybe we could deprecate the current dematerialize in Observable.
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Okay then. I'll change this to use the selector and post a separate PR for adding a selector variant to Observable/Flowable and deprecate the type-fragile versions.
| import io.reactivex.subjects.SingleSubject; | ||
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| public class SingleDematerializeTest { | ||
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| @Test | ||
| public void success() { | ||
| Single.just(Notification.createOnNext(1)) | ||
| .<Integer>dematerialize() | ||
| .dematerialize(Functions.<Notification<Integer>>identity()) |
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Too bad the identity function is inside an internal package :(
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I suppose most users now can use lambdas in their project so this is just v -> v for them. Only we are still so unlucky to use such helper methods.
This PR adds the
materializeoperator toMaybe,SingleandCompletableto turn their signals into the correspondingNotificationobject. This operator has been available forObservables (andFlowables) from the beginning of the Rx API. The methods returnSingle<Notification<T>>.To complement, the
dematerializeoperator is only defined forSingleand results in aMaybe.If accepted, I'll draw the correct marble diagrams for them in a separate PR.
Resolves: #6272