Golang Configuration

Config.go

// Bad
const bark = "woof"

type Dog struct{}

// Bark prints the dog's bark
func (d *Dog) Bark() {
  fmt.Println(bark)
}

// Better

const defaultBark = "woof"
type Dog struct {
  bark string
}

// Bark prints the dog's bark
func (d *Dog) Bark() {
  fmt.Println(d.bark)
}

// ConfigFunc are functions that can be used to configure a dog
type ConfigFunc func(*Dog)

// Bark sets the dog's barking sound
func Bark(bark string) ConfigFunc {
  return func(d *Dog) {
    d.bark = bark
  }
}

// ProvideDog provides a new Dog instance
func ProvideDog(configs ...ConfigFunc) *Dog {
  d := &Dog{defaultBark}
  for _, config := range configs {
    config(d)
  }
  return d
}

// Usage:
mydog := ProvideDog(Bark("guau"))