wiki/content/20200826142755-packages.md

date	id	title
2020-08-26	3123184d-c919-4cf6-8339-3f9b8ca5a1db	Golang Packages

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.