golang interface as namespace

person.go

package main

import (
	"fmt"
	"reflect"
)

type person struct {
	Name string
}
type BabyI interface {
	Crawling()
	GrowUp() BoyI
}
type BoyI interface {
	Playing()
	Older() ManI
}
type ManI interface {
	Working()
}

func (p *person) Crawling() {
	fmt.Printf("%s is crawling\n", p.Name)
}
func (p *person) Playing() {
	fmt.Printf("%s is playing\n", p.Name)
}
func (p *person) Working() {
	fmt.Printf("%s is working\n", p.Name)
}
func (p *person) GrowUp() BoyI {
	return reflect.ValueOf(p).Interface().(BoyI)
}
func (p *person) Older() ManI {
	return reflect.ValueOf(p).Interface().(ManI)
}
func NewBaby(name string) BabyI {
	return &person{Name: name}
}
func main() {
	baby := NewBaby("dd")
	baby.Crawling()
	baby.GrowUp().Playing()
	baby.GrowUp().Older().Working()
}