Go optional args, v2

gistfile1.go

package main

import (
	"fmt"
)

type Person struct {
	Name       string
	Age        int
	Position   string
	Department string
}

type PersonArg interface {
	AddArg(*Person)
}

type Age int
func (age Age) AddArg(p *Person) {
	p.Age = int(age)
}

type Position string
func (pos Position) AddArg(p *Person) {
	p.Position = string(pos)
}

type Department string
func (dep Department) AddArg(p *Person) {
	p.Department = string(dep)
}

func (p *Person) String() string {
	// terrible.
	pos := ""
	if p.Position != "" {
		pos = " - " + p.Position
	}
	dept := ""
	if p.Department != "" {
		dept = " " + p.Department
	}
	if p.Age == 0 {
		return p.Name + pos + dept
	}
	return fmt.Sprintf("%s (%d)%s%s", p.Name, p.Age, pos, dept)
}

func NewPerson(name string, args ...PersonArg) *Person {
	p := &Person{Name: name}
	for _, a := range args {
		a.AddArg(p)
	}
	return p
}

func main() {
	p := fmt.Println
	p(NewPerson("Steve"))
	p(NewPerson("Ajay",
		Department("Skunkworks"),
		Position("Engineer")))
	p(NewPerson("Dave",
		Age(43),
		Position("Tester")))
}

Yes, I proposed that awhile back too and was shot down.