Golang Packages

• Basics
• Imports
• Exported names

Basics

Every Go program is made up of packages. Programs start running in package main.

By convention the pacckage name is the same as the last element of the import path. For instance, the math/rand package comprises files that begin with the statement package rand.

package main
 
import (
	"fmt"
	"math/rand"
)
 
func main() {
	fmt.Println("My favorite number is", rand.Intn(10))
}

Imports

It’s best practice to convert multiple import statements to a “factored” import statement:

package main
 
import "fmt"
import "math"
 
func main() {
	fmt.Printf("This uses multiple import statements\n")
	fmt.Printf("Now you have %g problems.\n", math.Sqrt(7))
}

should be

package main
 
import (
	"fmt"
	"math"
)
 
func main() {
	fmt.Printf("This uses a parenthesized \"factored\" import statement\n")
	fmt.Printf("Now you have %g problems.\n", math.Sqrt(7))
}

Exported names

In Go, a name is exported if it begins with a capital letter. When importing a package, you can refer only to its exported names. Any “unexported” names are not accessible from outside the package.