Go - keep it to yourself - Encapsulation and Embedding - promoted methods

Head First Go
楽天ブックス 紀伊國屋書店

開発環境

• macOS Mojave - Apple (OS)
• Emacs (Text Editor)
• Windows 10 Pro (OS)
• Visual Studio Code (Text Editor)
• Go (プログラミング言語)

Head First Go (Jay McGavren(著)、O'Reilly Media)のChapter 10(keep it to yourself - Encapsulation and Embedding)、Exercise(314)の解答を求めてみる。

コード

landmark.go

package geo

import "errors"

type Landmark struct {
 name string
 Coordinates
}

func (l *Landmark) Name() string {
 return l.name
}
func (l *Landmark) SetName(name string) error {
 if name == "" {
  return errors.New("invalid name")
 }
 l.name = name
 return nil
}

sample3.go

package main

import (
 "fmt"
 "heafirstgo/geo"
 "log"
)

func main() {
 location := geo.Landmark{}
 err := location.SetName("The Googleplex")
 if err != nil {
  log.Fatal(err)
 }
 err = location.SetLatitude(37.42)
 if err != nil {
  log.Fatal(err)
 }
 err = location.SetLongitude(-122.08)
 if err != nil {
  log.Fatal(err)
 }
 fmt.Println(location.Name())
 fmt.Println(location.Latitude())
 fmt.Println(location.Longitude())
}

入出力結果(Bash、cmd.exe(コマンドプロンプト)、Terminal)

$ go run sample3.go
The Googleplex
37.42
-122.08
$