Go

Requirements

• Go 1.23.x (rilis 2x setahun, Feb & Agustus) — cek go.dev/dl

go version

Module & command

go mod init github.com/user/project
go get github.com/google/uuid
go mod tidy
go run main.go
go build -o app
go test ./...
go fmt ./...
go vet ./...

Variabel & tipe

var name string = "SaidQB"
age := 8                                    // type inference
const Pi = 3.14
var tags = []string{"go", "python", "php"}
config := map[string]bool{"debug": true}

Control flow

if age >= 18 { ... } else if age >= 13 { ... } else { ... }

for i := 0; i < 5; i++ { ... }
for _, tag := range tags { ... }
for { ... break }                            // infinite loop

switch status {
case "active": ...
case "inactive": ...
default: ...
}

Function, struct, method

func divide(a, b float64) (float64, error) {
    if b == 0 {
        return 0, errors.New("division by zero")
    }
    return a / b, nil
}

type User struct {
    Name  string
    Email string
}

func (u User) Greet() string { return "Halo, " + u.Name }       // value receiver
func (u *User) SetName(n string) { u.Name = n }                  // pointer receiver

Interface

type Animal interface {
    Sound() string
}

type Cat struct{}
func (c Cat) Sound() string { return "Meow" }

Goroutine & channel

ch := make(chan string)
go func() { ch <- "done" }()
msg := <-ch

var wg sync.WaitGroup
wg.Add(1)
go func() {
    defer wg.Done()
    // kerjaan
}()
wg.Wait()

var mu sync.Mutex
mu.Lock(); defer mu.Unlock()

Error handling

if err != nil {
    return fmt.Errorf("failed to fetch user: %w", err)   // wrap error
}

errors.Is(err, sql.ErrNoRows)
errors.As(err, &myErr)