XDR Enums?

[choubacha]

Thank you again for adding the data type maps, it really helps! I do have a question though, what data type should I use to express XDR C-like enums?

I thought that I could just make them c-like and it would work:

https://github.com/kbacha/clike-xdr-enums/blob/cd9995d0e8fbd317316e51be132f4ba5749f3f7e/src/main.rs#L5-L17

My thought was that the discriminant value of the enum could be used, but instead it was the ordinal position that was used:

$ cargo run
   Compiling test_serde_xdr v0.1.0 (file:///Users/kchoubacha/repos/kbacha/test_serde_xdr)
    Finished dev [unoptimized + debuginfo] target(s) in 0.53 secs
     Running `target/debug/test_serde_xdr`
Ok([0, 0, 0, 0])
Ok([0, 0, 0, 1])

One thing that I noticed when playing with enums in rust is that if the enum is all void types, then it's coercible to a i32. Possibly these values could be used as the discriminant then?

Another possibility is a serde derive attribute to set the discriminant value.

Thoughts?

[jvff]

Yes, this issue has a deeper problem. Serde doesn't help much here. There's a workaround example using macros (except that in this case it should serialize as either i32 or u32).

You can leave this issue open, I'll try to find a more ergonomic solution next week.

Thanks for the request!

[jvff]

Wow, I guess the week became a year 😅 Sorry for taking so long 😓

I believe I have found a workable solution. I created a separate crate (serde-enum) which can solve this. In theory, all that has to be done is import it and use #[derive(SerializeEnum, DeserializeEnum)] instead of the usual #[derive(Serialize, Deserialize)]. However, serde-xdr also needed a change, so for testing purposes you can add the following to your Cargo.toml:

[dependencies]
serde = "1.0"
serde-enum = { git = "https://github.com/jvff/serde-enum.git" }
serde-xdr = { git = "https://github.com/jvff/serde-xdr.git", branch = "ignore-enum-variant-names-feature", features = ["ignore-enum-variant-names"] }

Let me know if it works. I'll close this issue in a week or so if there are no new developments :)