Add `FlattenStrategy.race` #233

inamiy · 2017-01-17T13:26:34Z

Implemented #138.

I'm still wondering whether .first is really a good naming since there's already a blocking func first().
I personally feel race is a better name.

RuiAAPeres · 2017-01-17T16:04:38Z

(I personally feel race is a better name)

flatten(.🚗)

andersio · 2017-01-17T16:38:40Z

The context & use site of the strategy & the operator are different enough not to be confusing IMO.

RuiAAPeres · 2017-01-17T21:27:42Z

Could it be called simply .amb? From a discoverability point of view, it would be easier (searching for Functional Reactive Programming amb would yield the right sort of information). For people that already know the .amb operator the name would be fine as well.

sharplet · 2017-01-17T21:32:10Z

What does "amb" actually mean? I personally feel it would be better to have a more intention-revealing name, and link back to the equivalent Rx version.

inamiy · 2017-01-17T22:56:39Z

(Build failure seems unrelated)

I also don't know what amb actually means, so I'm +1 for either .first or .race.
.race is more descriptive (used in RxPHP?), but .first is also good name in contrast to .latest.

mdiep · 2017-01-18T01:56:43Z

I'm guessing amb is short for ambivalent?

Edit: Nope, it's should for ambiguous. https://msdn.microsoft.com/en-us/library/hh211783(v=vs.103).aspx#Anchor_1

mdiep · 2017-01-17T13:28:42Z

Sources/Flatten.swift

@@ -31,6 +31,15 @@ public enum FlattenStrategy: Equatable {
 	/// The resulting producer will complete only when the producer-of-producers
 	/// and the latest producer has completed.
 	case latest
+
+	/// Only the events from the first input producer should be considered for


This is a little ambiguous. Should be "from the first input producer to send an event".

Updated comments in cf6c4eb.

mdiep · 2017-01-18T02:17:18Z

Sources/Flatten.swift

@@ -733,6 +754,124 @@ private struct LatestState<Value, Error: Swift.Error> {
 	var replacingInnerSignal: Bool = false
 }

+extension SignalProtocol where Value: SignalProducerProtocol, Error == Value.Error {
+	/// Returns a signal that forwards values from the first signal sent on
+	/// `self`, ignoring values sent on consecutive inner signals.


Likewise, I don't think this is an accurate description.

Updated comments in cf6c4eb.

mdiep · 2017-01-18T02:33:26Z

Sources/Flatten.swift

+
+private struct FirstState<Value, Error: Swift.Error> {
+	var outerSignalComplete: Bool = false
+	var innerSignalComplete: Bool = true


It seems a little weird to default this to true. It might be better to default to false and check for innerSignalComplete || active == nil in shouldComplete?

Thanks for this catch! I could remove this redundant flag now in 819550f.

mdiep · 2017-01-22T19:48:33Z

Sources/Flatten.swift

+			case .completed:
+				let shouldComplete: Bool = state.modify {
+					$0.outerSignalComplete = true
+					return $0.active == nil


What should the behavior be if the outer signal receives a signal, completes, but the inner signal hasn't sent an event?

I haven't written the test yet, but I think the result should be the same as:

it("should complete when the outer signal completes before sending any signals").
https://github.com/ReactiveCocoa/ReactiveSwift/pull/233/files#diff-9cd786f9e52e786771d96cf8c42d3befR1481

New test will be: it("should complete when the outer signal completes before inner signals send any event").

(I will also update ambiguous test titles too)

mdiep · 2017-01-22T19:55:27Z

I think I like race.

first conflicts with the instance method, but it's also a little ambiguous about whether it's the first signal to be sent or the first signal to send an event. I suppose you could also get confused with race like that—but it seems a little more likely to direct you to the documentation.

inamiy · 2017-01-24T02:40:11Z

OK, I will rename to .race.

inamiy · 2017-01-24T22:00:29Z

In 9630f9f, I had to fix .completed behavior because scenario like #138 (comment) will complete immediately and this would be totally useless.

To fix that, I had to restore additional state var innerSignalComplete: Bool = true, and this flag basically checks the existence of at least one signal been started (doesn't care about value emission).

New `.completed` behavior of `SignalProducer.flatten(.race)`

If outer producer completes before any inner producer is created, complete immediately.
If outer producer completes after inner producer is created, complete after inner producer is completed.
If inner producer completes, complete after outer producer is completed.

mdiep · 2017-01-25T14:11:12Z

This is a breaking change because it adds a `case` to an existing `enum`.

This either needs to wait until we're ready for 2.0 on master or it needs to target a 2.0 branch.

andersio · 2017-01-25T16:18:07Z

The PR should target master-next in this case, hmm?

mdiep · 2017-03-31T11:46:29Z

@inamiy Would you mind resolving the conflicts here? I think this is ready to be merged to master for a 2.0 release.

NachoSoto · 2017-03-31T15:50:39Z

Sorry if I'm late commenting on this, but does this really add value? Isn't this equivalent to:

signal
  .take(first: 1)
  .flatten(anyStrategy)

andersio · 2017-03-31T15:58:29Z

No, your snippet takes only one inner signal and flattens it. race accepts any arbitrary amount of inner signals, flattens the first one that sends events, and disposes of the rest.

mdiep · 2017-03-31T16:04:56Z

Sorry if I'm late commenting on this, but does this really add value? Isn't this equivalent to:

Discussion here last time you asked this. 😉

NachoSoto · 2017-03-31T18:17:45Z

OMG lol, that's embarrassing @mdiep 😓

NachoSoto · 2017-03-31T18:17:58Z

Ship it then :D

inamiy · 2017-03-31T22:52:47Z

Rebase done in 76d457e 😉 (but CI alive?)

andersio · 2017-04-01T07:13:20Z

Reopen to trigger CI.

andersio · 2017-04-01T16:16:42Z

Sources/Flatten.swift

+						guard isWinningSignal else { return }
+
+						// Dispose all running innerSignals except winning one.
+						disposableHandle.remove()


Is it possible to make these not run for every event? They just need to be run once after all.

Done in 1b83292.

andersio · 2017-04-01T16:21:26Z

Sources/Flatten.swift

+
+					innerSignal.observe { [unowned innerSignal] event in
+
+						let isWinningSignal: Bool = state.modify {


Please name the arguments for multi-line closures.

Done in 1b83292.

andersio · 2017-04-01T16:21:47Z

Sources/Flatten.swift

+
+						switch event {
+						case .completed:
+							let shouldComplete: Bool = state.modify {


andersio · 2017-04-01T16:21:55Z

Sources/Flatten.swift

+				observer.send(error: error)
+
+			case .completed:
+				let shouldComplete: Bool = state.modify {


mdiep reviewed Jan 18, 2017

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RuiAAPeres added the enhancement label Jan 18, 2017

mdiep reviewed Jan 22, 2017

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mdiep added this to the 2.0 milestone Jan 22, 2017

andersio modified the milestone: 2.0 Jan 23, 2017

mdiep approved these changes Jan 25, 2017

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mdiep added this to the 2.0 milestone Jan 25, 2017

inamiy changed the title ~~Add FlattenStrategy.first~~ Add FlattenStrategy.race Jan 25, 2017

Add FlattenStrategy.race

76d457e

inamiy force-pushed the FlattenStrategy.first branch from 9630f9f to 76d457e Compare March 31, 2017 22:40

andersio closed this Apr 1, 2017

andersio reopened this Apr 1, 2017

andersio requested changes Apr 1, 2017

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andersio reviewed Apr 1, 2017

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Improve code

1b83292

andersio approved these changes Apr 2, 2017

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andersio merged commit 6f6787c into ReactiveCocoa:master Apr 2, 2017

inamiy deleted the FlattenStrategy.first branch April 4, 2017 09:29

andersio mentioned this pull request Apr 13, 2017

amb (race) as a new FlattenStrategy #138

Closed

andersio mentioned this pull request Jun 17, 2017

Extensible FlattenStrategy. #459

Merged

inamiy mentioned this pull request Nov 10, 2017

[Idea] Add FlattenStrategy.throttle #549

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inamiy mentioned this pull request Mar 6, 2019

Add FlatMapStrategy.throttle #713

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Add `FlattenStrategy.race` #233

Add `FlattenStrategy.race` #233

inamiy commented Jan 17, 2017 •

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RuiAAPeres commented Jan 17, 2017 •

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andersio commented Jan 17, 2017 •

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RuiAAPeres commented Jan 17, 2017

sharplet commented Jan 17, 2017

inamiy commented Jan 17, 2017

mdiep commented Jan 18, 2017 •

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mdiep Jan 17, 2017

inamiy Jan 18, 2017

mdiep Jan 18, 2017

inamiy Jan 18, 2017

mdiep Jan 18, 2017

inamiy Jan 18, 2017

mdiep Jan 22, 2017

inamiy Jan 24, 2017

inamiy Jan 24, 2017

mdiep commented Jan 22, 2017

inamiy commented Jan 24, 2017

inamiy commented Jan 24, 2017

mdiep commented Jan 25, 2017

andersio commented Jan 25, 2017

mdiep commented Mar 31, 2017

NachoSoto commented Mar 31, 2017

andersio commented Mar 31, 2017 •

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mdiep commented Mar 31, 2017

NachoSoto commented Mar 31, 2017

NachoSoto commented Mar 31, 2017

inamiy commented Mar 31, 2017

andersio commented Apr 1, 2017

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inamiy Apr 2, 2017

andersio Apr 1, 2017

inamiy Apr 2, 2017

andersio Apr 1, 2017

andersio Apr 1, 2017


		innerSignal.observe { [unowned innerSignal] event in

		let isWinningSignal: Bool = state.modify {

Add FlattenStrategy.race #233

Add FlattenStrategy.race #233

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inamiy commented Jan 17, 2017 • edited Loading

RuiAAPeres commented Jan 17, 2017 • edited Loading

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mdiep commented Jan 22, 2017

inamiy commented Jan 24, 2017

inamiy commented Jan 24, 2017

New .completed behavior of SignalProducer.flatten(.race)

mdiep commented Jan 25, 2017

This is a breaking change because it adds a case to an existing enum.

andersio commented Jan 25, 2017

mdiep commented Mar 31, 2017

NachoSoto commented Mar 31, 2017

andersio commented Mar 31, 2017 • edited Loading

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Add `FlattenStrategy.race` #233

Add `FlattenStrategy.race` #233

inamiy commented Jan 17, 2017 •

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RuiAAPeres commented Jan 17, 2017 •

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andersio commented Jan 17, 2017 •

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mdiep commented Jan 18, 2017 •

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New `.completed` behavior of `SignalProducer.flatten(.race)`

This is a breaking change because it adds a `case` to an existing `enum`.

andersio commented Mar 31, 2017 •

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