Composition Instead of Inheritance, golang

main.go

package main

import (
	"path"

	"github.com/gin-gonic/gin"
)

type oauthApp struct {
	Prefix string
	APIKey string
	APISecret string
}

func (a *oauthApp) key(c *gin.Context) {
	c.JSON(200, gin.H{"prefix": a.Prefix, "apikey": a.APIKey})
}

func (a *oauthApp) sec(c *gin.Context) {
	c.JSON(200, gin.H{"prefix": a.Prefix, "apisec": a.APISecret})
}

func (a *oauthApp) reg(r *gin.Engine){
	r.GET(path.Join(a.Prefix, "/key"), a.key)
	r.GET(path.Join(a.Prefix, "/sec"), a.sec)
}

type newApp struct{
	*oauthApp
	Value string
}

func (a *newApp) value(c *gin.Context) {
	c.JSON(200, gin.H{"prefix": a.Prefix, "value": a.Value})
}

func (a *newApp) reg(r *gin.Engine) {
	a.oauthApp.reg(r)
	r.GET(path.Join(a.Prefix, "/value"), a.value)
}

type oldApp struct{
	*oauthApp
	Value2 string
}

func (a *oldApp) value(c *gin.Context) {
	c.JSON(200, gin.H{"prefix": a.Prefix, "value": a.Value2})
}

func (a *oldApp) reg(r *gin.Engine) {
	a.oauthApp.reg(r)
	r.GET(path.Join(a.Prefix, "/value2"), a.value)
}

func main(){
	r := gin.Default()
	app1 := newApp{
		oauthApp:&oauthApp{
			Prefix: "/app1",
			APIKey: "apikey1",
			APISecret: "apisecret1",
		},
		Value: "value1",
	}

	app2 := oldApp{
		oauthApp:&oauthApp{
			Prefix: "/app2",
			APIKey: "apikey2",
			APISecret: "apisecret2",
		},
		Value2: "value2",
	}

	app1.reg(r)
	app2.reg(r)
	r.Run(":4000")
}