Publish LifecycleRegistry's ordering invariant for LifecycleObserver calls in its API documentation [141639111]

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to...@google.com

created issue #1

Sep 25, 2019 09:45PM

The invariant stated in LifecycleRegistry.java regarding ordering of observer invocation wrt. the ordering of #addObserver calls is a useful property to rely on (e.g. when there are inter-dependencies between 2+ observers of the same Lifecycle), but it's not clear from the API docs that this ordering guarantee exists, or will always exist.

https://android.googlesource.com/platform/frameworks/support/+/androidx-master-dev/lifecycle/lifecycle-runtime/src/main/java/androidx/lifecycle/LifecycleRegistry.java#52

> Invariant: at any moment of time for observer1 & observer2: if addition_order(observer1) < addition_order(observer2), then state(observer1) >= state(observer2)

If it's expected that this invariant will always hold, it seems worth adding to the API documentation.

Comments

[Deleted User] <[Deleted User]> #2Nov 29, 2019 02:46AM

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se...@google.com <se...@google.com> #3Jun 1, 2020 07:04PM

Just FYI, yeah it is strong guarantee that was specially designed this way. I keep it open as request to improve documentation

il...@google.com <il...@google.com> Nov 18, 2021 10:12PM

Status: New

jb...@google.com <jb...@google.com> Feb 9, 2022 03:52PM

Assigned to al...@google.com.

al...@google.com <al...@google.com> Jun 17, 2022 09:11PM

Reassigned to ja...@google.com.

Issue 141639111