git interface & struct embedding

main.go

package main

import "fmt"

type Resulter interface {
	GetResult() string
}

type DefaultResulter struct {
	Resulter
}

func (r *DefaultResulter) GetResult() string {
	return "def result"
}

type IntResulter struct {
	DefaultResulter
	intRes int
}

func (r *IntResulter) GetResult() string {
	res := fmt.Sprintf("int res = %d", r.intRes)
	r.intRes = r.intRes + 2
	return res
}

func main() {
	d := DefaultResulter{}
	println("d.Resulter == nil:", d.Resulter == nil)
	println("d.GetResult():", d.GetResult())
	println()

	var r Resulter = &d
	println("r Resulter = &d, r.GetResult():", r.GetResult())
	println()

	i := IntResulter{intRes: 42}
	println("i.Resulter == nil:", i.Resulter == nil)
	println("i.GetResult():", i.GetResult())
	println("i.DefaultResulter.GetResult():", i.DefaultResulter.GetResult())
	println("i.DefaultResulter.Resulter:", i.DefaultResulter.Resulter)
	println()


	var r2 Resulter = &i
	println("r2 Resulter = &i, i.GetResult():", r2.GetResult())
	println("r2.GetResult():", r2.GetResult())
	println("r2.GetResult():", r2.GetResult())
	println("r2.GetResult():", r2.GetResult())
}