Goの構造体の研究 ref: http://qiita.com/kmtr/items/1e7caf92aa8bb587906d

file0.go

type Account struct {
    Email    string
    Password string
    Rank     int
}

file1.go

func main() {
    account := new(Account)
    account.Email = "sample@example.com"
    account.Password = "password"
    account.Rank = 1
    fmt.Printf("%v", account)
}

file10.go

type AccountParam struct {
    Account
    PasswordCurrent string `json:"password_current"`
    Rank            int    `json:"user_rank"`
}

file11.go

package main

type Account struct {
    Email    string `json:"email"`
    Password string `json:"password"`
    Rank     int    `json:"rank"`
}

type AccountParam struct {
    Account
    PasswordCurrent string `json:"password_current"`
}

func main() {
    var a *Account
    a = new(AccountParam)
}

file12.go

func main() {
    a := AccountParam{}
    b := Account{}

    a.Account = b

    fmt.Println(a)
}

file2.go

func main() {
    account := &Account{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }
    fmt.Printf("%v", account)
}

file3.go

func main() {
    account := Account{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }
    fmt.Printf("%v", account)
}

file4.go

package main

import "fmt"

type Account struct {
    Email    string
    Password string
    Rank     int
}

func updatePassword(account Account, password string) {
    account.Password = password
    fmt.Printf("account.Password(func)  : %s\n", account.Password)
    fmt.Printf("account.Password(pointer): %p\n", &account)
}

func updatePasswordP(account *Account, password string) {
    account.Password = password
    fmt.Printf("accountP.Password(func)  : %s\n", account.Password)
    fmt.Printf("accountP.Password(pointer): %p\n", account)
}

func main() {
    account := Account{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }
    fmt.Printf("account.Password(pointer): %p\n", &account)
    fmt.Printf("account.Password(before): %s\n", account.Password)
    updatePassword(account, "new password")
    fmt.Printf("account.Password(after) : %s\n", account.Password)

    fmt.Println("-----------------")
    accountP := &Account{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }
    fmt.Printf("accountP.Password(pointer): %p\n", accountP)
    fmt.Printf("accountP.Password(before): %s\n", accountP.Password)
    updatePasswordP(accountP, "new password")
    fmt.Printf("accountP.Password(after) : %s\n", accountP.Password)
}

file5.txt

$ go run ac.go 
account.Password(pointer): 0xc420014150
account.Password(before): password
account.Password(func)  : new password
account.Password(pointer): 0xc420014180
account.Password(after) : password
-----------------
accountP.Password(pointer): 0xc4200141b0
accountP.Password(before): password
accountP.Password(func)  : new password
accountP.Password(pointer): 0xc4200141b0
accountP.Password(after) : new password

file6.txt

{"Email":"sample@example.com","Password":"password","Rank":1}

file7.go

package main

import (
    "bytes"
    "encoding/json"
    "fmt"
)

type Account struct {
    Email    string `json:"email"`
    Password string `json:"password"`
    Rank     int    `json:"rank"`
}

func main() {
    account := &Account{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }

    // encode
    buf := new(bytes.Buffer)
    json.NewEncoder(buf).Encode(account)
    fmt.Println(buf.String())

    // decode
    decoded := new(Account)
    json.NewDecoder(buf).Decode(decoded)
    fmt.Println(decoded)
}
// 実行結果
// {"email":"sample@example.com","password":"password","rank":1}
//
// &{sample@example.com password 1} 

file8.go

// package, import, Account構造体定義省略

type UserAccount Account

func main() {
    account := &UserAccount{
        Email:    "sample@example.com",
        Password: "password",
        Rank:     1,
    }

    // encode
    buf := new(bytes.Buffer)
    json.NewEncoder(buf).Encode(account)
    fmt.Println(buf.String())

    // decode
    decoded := new(UserAccount)
    json.NewDecoder(buf).Decode(decoded)
    fmt.Println(decoded)
}
// 実行結果
// {"email":"sample@example.com","password":"password","rank":1}
//
// &{sample@example.com password 1}

file9.go

// package, import, Account構造体定義省略

type AccountParam struct {
    Account
}

func main() {
    account := new(AccountParam)
    account.Email = "sample@example.com"
    account.Password = "password"
    account.Rank = 

    // encode
    buf := new(bytes.Buffer)
    json.NewEncoder(buf).Encode(account)
    fmt.Println(buf.String())

    // decode
    decoded := new(AccountParam)
    json.NewDecoder(buf).Decode(decoded)
    fmt.Println(decoded)
}
// 実行結果
// {"email":"sample@example.com","password":"password","rank":1}
//
// &{sample@example.com password 1}