Writing a Ruby extension in Go (golang)

Question

Are there some tutorials or practical lessons on how to write an extension for Ruby in Go?

Answer 1

Go 1.5 added support for building shared libraries that are callable from C (and thus from Ruby via FFI). This makes the process easier than in pre-1.5 releases (when it was necessary to write the C glue layer), and the Go runtime is now usable, making this actually useful in real life (goroutines and memory allocations were not possible before, as they require the Go runtime, which was not useable if Go was not the main entry point).

goFuncs.go:

package main

import "C"

//export GoAdd
func GoAdd(a, b C.int) C.int {
    return a + b
}

func main() {} // Required but ignored

Note that the //export GoAdd comment is required for each exported function; the symbol after export is how the function will be exported.

goFromRuby.rb:

require 'ffi'

module GoFuncs
  extend FFI::Library
  ffi_lib './goFuncs.so'
  attach_function :GoAdd, [:int, :int], :int
end

puts GoFuncs.GoAdd(41, 1)

The library is built with:

go build -buildmode=c-shared -o goFuncs.so goFuncs.go

Running the Ruby script produces:

42