Otto JS Plugin - expose host object to JS

gistfile1.go

package main

import (
	"bytes"
	"fmt"
	"log"
	"os"

	"github.com/robertkrimen/otto"
)

type BensObject struct {
	name string
}

func (b BensObject) SetName(name string) {
	fmt.Println("INT: ", name)
	b.name = name
	fmt.Println("INT: ", b.name)
}

func (b BensObject) GetName() string {
	fmt.Println("INT: ", b.name)
	return b.name
}

func (b BensObject) Age() int {
	return 36
}

func (b BensObject) AddToAge(n int) int {
	return 36 + n
}

func main() {
	runtime := loadPluginRuntime("plugins.js")

	// If we don't have a runtime all requests are accepted
	if runtime == nil {
		os.Exit(-1)
	}

	r := new(BensObject)
	v, err := runtime.ToValue(*r)
	if err != nil {
		log.Fatal(err)
	}

	// By convention we will require plugins have a set name
	result, err := runtime.Call("checkRequest", nil, v)
	if err != nil {
		log.Fatal(err)
	}
	// If the js function did not return a bool error out
	// because the plugin is invalid
	out, err := result.ToBoolean()
	if err != nil {
		log.Fatalf("\"checkRequest\" must return a boolean. Got %s", err)
	}

	fmt.Println(out)
}

func loadPluginRuntime(name string) *otto.Otto {
	f, err := os.Open(name)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		log.Fatal(err)
	}
	defer f.Close()
	buff := bytes.NewBuffer(nil)

	if _, err := buff.ReadFrom(f); err != nil {
		log.Fatal(err)
	}
	runtime := otto.New()
	// Load the plugin file into the runtime before we
	// return it for use
	if _, err := runtime.Run(buff.String()); err != nil {
		log.Fatal(err)
	}
	return runtime
}