Exercise 6: Using Packages and Modules in Go

Why Use Packages and Modules?

Packages and modules help structure your code, make it reusable, and efficiently manage dependencies.

Creating a Package in Go

A package is a collection of Go files grouped in the same directory. Here’s an example of a `mathutils` package:

// File: mathutils/mathutils.go
package mathutils

// Addition adds two numbers
func Addition(a, b int) int {
    return a + b
}

Importing and Using a Package

After creating a package, you can use it in another file:

package main

import (
    "fmt"
    "myproject/mathutils"
)

func main() {
    result := mathutils.Addition(5, 3)
    fmt.Println("Result:", result)
}

Managing Modules with `go mod`

Go uses `go mod` to manage external and internal dependencies.

go mod init myproject

The `go.mod` file identifies a Go project as a module.

Exercise Instructions

• Create a file main.go and a folder `mathutils`.
• Add an `Addition` function inside `mathutils.go`.
• Import and use this function in `main.go`.
• Initialize a Go module with `go mod init`.

Expected Output

Result: 8

Best Practices for Packages and Modules in Go

• ✅ Use **meaningful names** for packages.
• ✅ **Group related functions** in the same package.
• ✅ Use `go mod tidy` to clean unused dependencies.
• ✅ Follow Go's **naming conventions** (`lowercase` package names).

📚 Learn more about Go packages and modules:

Official Go Documentation