go修行13日目 Package

Package

• 1階層

awesomeProject/
├── main.go
└── mylib
    └── math.go

main.go

package main

import (
    "awesomeProject/mylib"
    "fmt"
)

func main() {
    s := []int{1, 2, 3, 4, 5}
    fmt.Println(mylib.Average(s))
}

math.go

package mylib

func Average(s []int) int {
    total := 0
    for _, i := range s {
        total += i
    }
    return int(total / len(s))
}

結果

3

• 2階層

階層

awesomeProject/
├── main.go
└── mylib
    ├── human.go
    ├── math.go
    └── under
        └── sub.go

main.go

package main

import (
    "awesomeProject/mylib"
    "awesomeProject/mylib/under"
    "fmt"
)

func main() {
    s := []int{1, 2, 3, 4, 5}
    fmt.Println(mylib.Average(s))

    mylib.Say()
    under.Hello()
}

math.go

package mylib

func Average(s []int) int {
    total := 0
    for _, i := range s {
        total += i
    }
    return int(total / len(s))
}

human.go

package mylib

import "fmt"

func Say() {
    fmt.Println("Human!")
}

sub.go

package under

import "fmt"

func Hello() {
    fmt.Println("Hello!")
}

出力

3
Human!
Hello!

Public,Private

• 外部から利用する場合にはPublicのように頭は大文字

main.go

package main

import (
    "awesomeProject/mylib"
    "awesomeProject/mylib/under"
    "fmt"
)

func main() {
    s := []int{1, 2, 3, 4, 5}
    fmt.Println(mylib.Average(s))

    mylib.Say()
    under.Hello()
    person := mylib.Person{Name: "Mike", Age: 20}
    fmt.Println(person)

    fmt.Println(mylib.Public)
    fmt.Println(mylib.private)
}

human.go

package mylib

import "fmt"

var Public string = "Public"
var private string = "private"

type Person struct {
    Name string
    Age  int
}

func Say() {
    fmt.Println("Human!")
}

出力

• privateは頭が小文字でunexpotedと出ている

.\main.go:19:14: cannot refer to unexported name mylib.private
.\main.go:19:14: undefined: mylib.private