Refactored & Bugfix: startWithSignal and the hot-to-cold lift.
#106
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andersio
changed the title
startWithSignal and refactored the hot-to-cold lift.startWithSignal and the hot-to-cold lift.
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Any chance you can add a test case for the actual hug you fixed? 🙏 |
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Added in f626658. Though you might have already seen a bunch of test cases that failed and needed a change because of the fix. |
| outerDisposable += transform(signal)(wrapperSignal).observe(observer) | ||
| } | ||
| } | ||
| return self.liftRight(transform)(SignalProducer(signal: otherSignal)) |
| @@ -1970,6 +1988,7 @@ class SignalProducerSpec: QuickSpec { | |||
| producer | |||
| .observe(on: TestScheduler()) | |||
| .startWithSignal { signal, innerDisposable in | |||
| signal.observe { _ in } | |||
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Under the new signal lifetime semantic, a signal is kept alive only if it is retained or has active observers. So the observer is added to extend the signal's lifetime indefinitely for the termination event outside the closure scope, or otherwise the signal would dispose of itself upon exiting the closure.
The fixed bug is kinda related too - a produced signal would dispose of itself when it is not retained and not observed. But then the associated producer disposable would not follow.
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RAC 4.0: The signal is alive until a termination event or a user interruption. producer.startWithSignal { _ in }
let d = SimpleDisposable()
var disposed = false
SignalProducer { _, pd in pd += d }
.on(disposed: { disposed = true })
.startWithSignal { _ in }
var signal: Signal!
producer.startWithSignal { signal = $0 }
producer.startWithSignal { $0.observe { _ in } } |
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Awesome |
startWithSignalOne less layer of wrapping = more joules saved.
Breaking ChangeBugfixIf the signal created & passed to the
setUpclosure is neither retained nor observed, the producer disposable would be disposed of.Detailed Example: #106 (comment)
Due to the new signal lifetime semantics in 1.0, the signal would have been disposed of upon exiting the scope of the closure. But the producer disposable does not follow the disposal of the produced signal - it is only disposed of until the upstream sends a termination event, or the producer is interrupted by the user.
In other words, it doesn't match the expected behaviour of
SignalProducerhaving downstream disposals propagated back to the upstream.This fix should IMO hardly affect any existing use case though, since the closure based
starts are way more popular.liftthat returns(Signal) -> SignalProducerThe signal is lifted as a producer (so it becomes interruptible) before applying the transform.