Change onBecome(Un)Observed implementation to work with multiple listeners #1771
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mweststrate
requested changes
Oct 18, 2018
| private unobservedListeners?: Set<Function> | ||
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| get onBecomeObservedListeners(): Set<Function> { | ||
| if (this.observedListeners === undefined) this.observedListeners = new Set() |
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The getter causes the set to be initializaed lazily, but effectively for every atom, correct (as MobX core will often inspect this getter)? So this means that every atom now will have an additional Set to allocate.
I would prefer to see a solution that doesn't allocate the Set (or just a shared, empty, frozen one), until the first listeners is established, and only then instantiate the local Set of listeners
5 tasks
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Closed in favor of #1833 |
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This PR fixes #1537
PR checklist:
gh-pagesbranch. Please refer to this PR). For new functionality, at least API.md should be updatednpm run perf)In this PR I've changed the implementation of onBecomeObserved and onBecomeUnobserved to allow for unsubscribing previous subscription.
In the new implementation I keep the listeners in Sets rather than create a chain of calls as previously.
Also for performance reasons I've created custom getters that lazily initialise the Sets.
This might break external libraries that implement on IObservable. I thought about instead of changing the interface of IObservable, add a custom
getterandsettertoonBecomeObservedandonBecomeUnobservedto keep the previous interface but I decided to wait for a hint from you to decide on that.