GoudEngine Proc Macros

Procedural macro crate providing the #[goud_api] attribute for auto-generating FFI wrapper functions from annotated impl blocks.

Purpose

Eliminates hand-written #[no_mangle] extern "C" boilerplate. Annotate an impl block and the macro generates the FFI wrappers, null checks, context lookups, and a JSON manifest consumed by the codegen pipeline.

Usage

#[goud_api(module = "window")]
impl GoudGame {
    pub fn should_close(&self) -> bool { /* ... */ }
    pub fn poll_events(&mut self) -> GoudResult<f32> { /* ... */ }
}

This generates:

goud_window_should_close(ctx: GoudContextId) -> bool
goud_window_poll_events(ctx: GoudContextId, out: *mut f32) -> GoudResult
A JSON manifest entry for each function (collected into codegen/ffi_manifest.json)

Attributes

Block-level (on `impl`)

Attribute	Required	Effect
`module = "name"`	Yes	Sets FFI function prefix: `goud_<module>_<method>`
`feature = "native"`	No	Wraps generated FFI in `#[cfg(feature = "...")]`

Method-level (on `fn`)

Attribute	Effect
`#[goud_api(skip)]`	Excludes method from FFI generation
`#[goud_api(name = "custom")]`	Overrides the method name in the FFI function

Build Integration

The macro emits manifest metadata as const strings per module
build.rs in goud_engine collects these manifest constants
Combined output is written to codegen/ffi_manifest.json
Codegen scripts (gen_csharp.py, gen_python.py, etc.) read the manifest

Crate Type

This is a proc-macro = true crate. It depends on syn, quote, proc_macro2, serde, and serde_json. It has no runtime dependency on the engine.

goud_engine_macros 0.0.841