Safe idiomatic Rust API for plugins + embedding

[v3xro]

I would like to use KCL as the configuration language for my application written in Rust. I think the following features would be nice to have:

• serde Deserialize support from ValueRef -> native rust struct/enum (I have a prototype version that I might share once it's better tested)
• Safe idiomatic interface for plugin functions (that is not extern "C") - I guess a macro could be made that allows you to write functions with types like fn my_plugin_function(a: String, b: i64) -> Option<String> that then converts this to extern "C" my_plugin_function(ctx: *mut kclvm_context_t, ...)
• Better binding for loading config (that does not go through the protobuf/kclvm interface such as the rust lib currently does)
• Ability to customise builtin modules (e.g. limiting the file/environment read functionality by making it unavailable)

Happy to expand on all of these - am currently trying to integrate KCL in such a way and doubtless these ideas will evolve and I will have some working code to demonstrate how to do this currently.

[Peefy]

Hello @v3xro

I'm glad to see more integration and development of KCL Rust. I think these improvements are very helpful. 👍 Feel free to raise more issues or PRs, and we can further make more changes. ❤️

[v3xro]

Do you have a good example of how to register a plugin in Rust? kclvm_plugin_init seems to want to do a roundtrip through json strings which I'd rather avoid.

[Peefy]

I've opened a PR and give the initial impl and example: #1599

[v3xro]

That look good - certainly better than what I've been trying (evaluator.add_or_update_global_variable("name_of_fun", ValueRef::func(...)))