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A runnable main.go that constructs the timer with a TimerConfig, then calls
Echo (struct param), Complex (slice-of-structs + slice + two optionals) and
Schedule (three struct params) with idiomatic Go values — the methods the Go
generator used to skip. The Makefile builds the dylib next to the package
(cgo's ${SRCDIR} rpath finds it at runtime); README documents the Nim->Go type
mapping. Verified end-to-end with `go run`.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
59 lines
1.9 KiB
Markdown
59 lines
1.9 KiB
Markdown
# Go (cgo) bindings — native (same-process) example
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Generated cgo bindings for the timer library. The Go wrapper links the library
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directly and calls the **native** C ABI, marshalling each `{.ffi.}` type from an
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idiomatic Go struct into its flat C-POD form per call.
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## Files
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| File | Description |
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|------|-------------|
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| `my_timer.go` | Generated cgo package. One Go struct per `{.ffi.}` type plus a `toC()` marshaller; one method per `{.ffi.}` proc. |
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| `my_timer.h` | Native C header (emitted alongside the `.go` so cgo's `#include` resolves locally). |
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| `go.mod` | Makes the package an importable module. |
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| `example/` | A runnable `main.go` that exercises the struct-param methods. |
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Regenerate with `nimble genbindings_go` (from the repo root); the files here are
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overwritten each time and `gofmt`-finalized.
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## Mapping
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| Nim (`{.ffi.}`) | Go |
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|-----------------|-----|
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| `string` | `string` |
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| `int` / `int64` … | `int64` … |
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| `bool` | `bool` |
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| `seq[T]` | `[]T` |
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| `Option[T]` / `Maybe[T]` | `*T` (nil = none) |
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| nested `{.ffi.}` struct | nested Go struct |
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Each call deep-copies its arguments across the FFI thread, so the Go-side C
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allocations are freed (via `defer`) as soon as the call returns. String-returning
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methods give back a Go `string`; struct-returning methods deliver their CBOR
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encoding (decode it with a Go CBOR library if needed).
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## Build & run
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```sh
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cd examples/timer/go_bindings
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make run
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```
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Expected output:
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```
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created timer
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version: nim-timer v0.1.0
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echo: ok (struct param round-tripped)
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complex: ok (seq/option graph deep-copied)
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schedule: ok (three struct params in one call)
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done
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```
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`Echo`, `Complex` and `Schedule` take `{.ffi.}` structs, slices and optionals
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directly — previously these procs were skipped by the Go generator.
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For the cross-process / cross-machine path (CBOR over a socket), see
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[`../ipc`](../ipc); a Go client could speak the same wire protocol using any Go
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CBOR library.
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