Type 'core::time::Duration' does not support ReflectValue serialization

[shelbyd]

What problem does this solve or what need does it fill?

I'm building a general purpose plugin for doing rollback networking for bevy and a game using that. To support clients reconnecting after disconnect, I need to serialize relevant state and transmit it to reconnecting clients. It's common for Timers to be relevant for gameplay logic, and those require serializing Durations.

What solution would you like?

Implement ReflectValue serialization for Duration and other core types.

What alternative(s) have you considered?

To unblock myself, I can reimplement Timer and Duration with a custom MyDuration type that derives Reflect. Doing that is not ideal for a myriad of reasons, but probably necessary to continue progress on my project.

[alice-i-cecile]

This is a very reasonable requirement. If you're comfortable with it, this should be a fairly straightforward PR.

[shelbyd]

If you can point me to the relevant file(s), I'm happy to do it myself.

[alice-i-cecile]

Usually, we'd just use a #[derive(Reflect)] macro invocation (as seen in the examples), but that won't work here, as we need to implement the trait for a foreign type.

Similarly, we can't put this in bevy_core with the other time logic, since we don't own the Reflect trait there.

I would probably start a new file (time.rs) in this folder and implement the trait there for Duration and Instant.

The other examples in that folder should provide a nice guide, but feel free to reach out here or on your PR if you run into difficulties.

[cart]

Duration is an std type, so it should probably go in the existing std module in the impls folder, but other than that I agree with @alice-i-cecile's recommendations.

[jcornaz]

I opened a PR that solves this issue. @shelbyd, I hope you don't mind that I didn't let you solve it yourself. I just stumbled into this problem too. And since the problem is pretty annoying, yet easy to fix, I just couldn't help but open a PR.