0a8b53a06d
Struct-returning methods now hand back a typed Go struct instead of the raw
CBOR/bytes. Since the native return POD is freed right after the callback, the
POD->Go conversion must happen in-callback: the generator emits a `fromC()`
reader per {.ffi.} type and, per struct-returning proc, an exported Go result
callback. The method calls the native entry point directly with that callback
and a `runtime/cgo.Handle` (boxed in a small C allocation so it travels through
the void* userData checkptr-safe), then blocks until the callback delivers the
typed value or error on the result slot.
String/raw-returning procs keep the existing C-bridge + condvar path. Validated
end-to-end (Echo/Complex/Schedule) including under `go run -race`.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Go (cgo) bindings — native (same-process) example
Generated cgo bindings for the timer library. The Go wrapper links the library
directly and calls the native C ABI, marshalling each {.ffi.} type from an
idiomatic Go struct into its flat C-POD form per call.
Files
| File | Description |
|---|---|
my_timer.go |
Generated cgo package. One Go struct per {.ffi.} type plus a toC() marshaller; one method per {.ffi.} proc. |
my_timer.h |
Native C header (emitted alongside the .go so cgo's #include resolves locally). |
go.mod |
Makes the package an importable module. |
example/ |
A runnable main.go that exercises the struct-param methods. |
Regenerate with nimble genbindings_go (from the repo root); the files here are
overwritten each time and gofmt-finalized.
Mapping
Nim ({.ffi.}) |
Go |
|---|---|
string |
string |
int / int64 … |
int64 … |
bool |
bool |
seq[T] |
[]T |
Option[T] / Maybe[T] |
*T (nil = none) |
nested {.ffi.} struct |
nested Go struct |
Each call deep-copies its arguments across the FFI thread, so the Go-side C
allocations are freed (via defer) as soon as the call returns. String-returning
methods give back a Go string; struct-returning methods deliver their CBOR
encoding (decode it with a Go CBOR library if needed).
Build & run
cd examples/timer/go_bindings
make run
Expected output:
created timer
version: nim-timer v0.1.0
echo: ok (struct param round-tripped)
complex: ok (seq/option graph deep-copied)
schedule: ok (three struct params in one call)
done
Echo, Complex and Schedule take {.ffi.} structs, slices and optionals
directly — previously these procs were skipped by the Go generator.
For the cross-process / cross-machine path (CBOR over a socket), see
../ipc; a Go client could speak the same wire protocol using any Go
CBOR library.