go test

gistfile1.txt

package main

import (
	"fmt"
	"reflect"
)

type AppInterface interface {
	run() *App
}

type App struct {
	attr string
}

func (self *App) run() *App {
	self.attr = "abc"
	return self
}

func f(app AppInterface) {
	fmt.Println(app)
}

func main() {
	var app AppInterface = new(App)
	var app1 *App = new(App)
	var app2 App

	fmt.Println(reflect.TypeOf(app), app)
	fmt.Println(reflect.TypeOf(app1), app1)
	fmt.Println(reflect.TypeOf(app2), app2)

	app.run()
	app1.run()
	app2.run()

	f(app)
	f(app1)
	f(&app2)

	fmt.Println(app.(*App).attr)
	fmt.Println(app1.attr)
	fmt.Println(app2.attr)

}