options.go

options.go

package main

import (
	"fmt"
)

type Options struct {
	foo int
	bar string
}

func DefaultOptions() *Options {
	return &Options{foo: 1, bar: "baz"}
}

func (o *Options) Foo(foo int) *Options {
	o.foo = foo
	return o
}

func (o *Options) Bar(bar string) *Options {
	o.bar = bar
	return o
}

func (o *Options) Value() Options {
	return *o
}

type Thing struct {
	Options
	// Can embed or directly set fields as necessary
}

func New(options Options) *Thing {
	// Use or embed options...
	return &Thing{Options: options}
}

func main() {
	t := New(DefaultOptions().Foo(2).Bar("qux").Value())
	fmt.Printf("Options %v", t.Options)
}

http://play.golang.org/p/fYHLLvL-jd