Paket lan modul apa ngenani organisasi kode Go?

Question

Accepted Answer

Go ngorganisir kode karo **packages** (koleksi file sumber ing direktori) lan **modules** (koleksi packages kanthi dependensi sing versioned). Bebarengan padha nstruktur proyek lan manage dependensi.

## Packages — direktori kode sing gegandhengan

```go
// every .go file starts by declaring its package
package main         // "main" is special — produces an executable

// or a library package (named after its directory, conventionally)
package mathutil

func Add(a, b int) int { return a + b }   // Exported (capitalized) — usable outside
func helper() {}                           // unexported (lowercase) — package-private
```

Semua file ing siji direktori nakung siji package. **Kapitalisasi ngontrol visibility**: jeneng sing dikkapitalisasi exported (publik manggone packages), lowercase pribadi kanggo package.

## Ngimp lan nggunakake packages

```go
import (
    "fmt"                          // standard library
    "strings"
    "github.com/user/repo/mathutil" // a third-party or local module package
)

fmt.Println(strings.ToUpper("hi"))
mathutil.Add(2, 3)                  // use Exported names via package.Name
```

## Modules — versioned dependency management

```bash
go mod init github.com/user/myapp   # create a module → makes go.mod
go get github.com/gin-gonic/gin     # add a dependency (records it in go.mod)
go mod tidy                          # add missing & remove unused dependencies
go build                             # build using the module's dependencies
```

```text
go.mod  — declares the module path, Go version, and direct dependencies (+ versions)
go.sum  — cryptographic checksums of dependencies (integrity/security)
```

A **module** (introduced ing Go 1.11) minangka unit saka dependency management — `go.mod` list versi dependensi sing pasti, nggawe builds reproducible. `go.sum` verifikasi dependency integrity.

## Fungsi init lan main

```go
package main

func init() {    // runs automatically when the package loads (before main)
    // setup
}
func main() {    // entry point of an executable (package main only)
}
```

## Konvensi struktur proyek

```text
myapp/
  go.mod
  main.go              package main
  internal/            packages here are PRIVATE to this module (can't be imported externally)
  pkg/ or other dirs/  reusable packages
```

Direktori `internal/` spesial — packages-ne bisa mung diimport ing samedhap modul, ngenforsi encapsulation ing tingkat modul.

## Mengapa iki penting

Packages lan modules minangka cara proyek Go distruktur lan cara dependensi dikelola — penting kanggo proyek nyata apa dene.

Pamahaman packages (direktori file, visibility exported/unexported adhedhasar kapitalisasi, package `main` sing spesial) iku dhasar kanggo organisir kode lan kontrol API publike.

Modules (`go mod`, `go.mod`/`go.sum`) nyedhiyakake dependency management sing reproducible, versioned, integrity-checked — standar modern sing ngganti pendekatan GOPATH lawas.

Weruhi sistem import, konvensi `internal/` kanggo kode modul-pribadi, lan tooling (`go mod init/tidy`, `go get`) iku perlu kanggo building, sharing, lan maintain proyek Go, lan bisa nggambarakke fluency praktis karo ekosistem Go.