教程

Install

https://golang.org/doc/install

Get started

https://golang.org/doc/tutorial/getting-started

mod初始化

go mod init MODULE_PATH

引入外部module

import "rsc.io/quote"

添加新外部module

go mod tidy

Create Module

https://golang.org/doc/tutorial/create-module

初始化

go mod init example.com/greetings

函数和变量定义

// Hello returns a greeting for the named person.
func Hello(name string) string {
    // Return a greeting that embeds the name in a message.
    message := fmt.Sprintf("Hi, %v. Welcome!", name)
    // or
    // var message string
    // message = fmt.Sprintf("Hi, %v. Welcome!", name)
    return message
}

在其它项目中引用

编辑go.mod

module example.com/hello

go 1.16

replace example.com/greetings => ../greetings

触发同步包

go mod tidy

处理错误

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return "", errors.New("empty name")
    }

    // If a name was received, return a value that embeds the name
    // in a greeting message.
    message := fmt.Sprintf("Hi, %v. Welcome!", name)
    return message, nil
}

func main() {
    // Set properties of the predefined Logger, including
    // the log entry prefix and a flag to disable printing
    // the time, source file, and line number.
    log.SetPrefix("greetings: ")
    log.SetFlags(0)

    // Request a greeting message.
    message, err := greetings.Hello("")
    // If an error was returned, print it to the console and
    // exit the program.
    if err != nil {
        log.Fatal(err)
    }

    // If no error was returned, print the returned message
    // to the console.
    fmt.Println(message)
}

常见数据结构

slices

formats := []string{
        "Hi, %v. Welcome!",
        "Great to see you, %v!",
        "Hail, %v! Well met!",
    }

cases := []struct {
		in, want string
	}{
		{"Hello, world", "dlrow ,olleH"},
		{"Hello, 世界", "界世 ,olleH"},
		{"", ""},
	}    

map

messages := make(map[string]string)

testing

import (
    "testing"
)

// TestHelloEmpty calls greetings.Hello with an empty string,
// checking for an error.
func TestHelloEmpty(t *testing.T) {
    msg, err := Hello("")
    if msg != "" || err == nil {
        t.Fatalf(`Hello("") = %q, %v, want "", error`, msg, err)
    }
}

go test -v

build

go build

install

检查安装地址

go list -f '{{.Target}}'

go install