How Can I Keep Native State?

[coder0xff]

From what I can gather, references and pointers can't be used as arguments or return values. If, for example, I were to open a database connection in Rust, and the handle struct contained private, non-serializable fields, it becomes pretty difficult to pass it around between Flutter -> Rust invocations. The only workaround I'm aware of is converting pointers to usize. And since generics aren't supported, type safety can't be preserved by something like struct UintPtr<DBHandle>. Needless to say, that's really undesirable.

Is there a clean way to keep the native state connected to an object that passes through the bridge?

[fzyzcjy]

Maybe opaque, or lazy_static, or pool

[coder0xff]

I can guess how pool would work, using an integer to reference an allocated slot in a pool. I have the basic idea behind lazy_static (I'm fairly new to Rust and Flutter/Dart), but I don't know how I would use it here. If my intuition is right, opaque seems like it could be what I'm looking for. Is there an example showing it in this use case?

[fzyzcjy]

please have a look at the doc :)

[coder0xff]

Found it in https://cjycode.com/flutter_rust_bridge/feature/lang_rust_opaque.html