Go without Tooling System

README.go

## セットアップ

```bash
$ mkdir bin
$ go run tools.go
```

## 実行

```bash
$ bin/gin --appPort 8080 run go run main.go
```

main.go

package main

import (
	"net/http"

	"github.com/labstack/echo"
)

func main() {
	e := echo.New()
	e.GET("/", func(c echo.Context) error {
		return c.String(http.StatusOK, "Hello, World!")
	})
	e.Logger.Fatal(e.Start(":8080"))
}

tools.go

// +build tools

package main

import (
	"fmt"
	"os"
	"os/exec"
	"strings"

	_ "github.com/codegangsta/gin/lib" // これは微妙な書き方かもしれない
)

func main() {
	install_bin("gin", "github.com/codegangsta/gin")
	teardown()
}

func install_bin(bin_name string, package_name string) {
	bin_location := fmt.Sprintf("bin/%s", bin_name)

	cmd := exec.Command("go", "build", "-o", bin_location, package_name)
	out, err := cmd.CombinedOutput()

	fmt.Printf("cmd: %s\n", strings.Join(cmd.Args, " "))
	fmt.Printf("out: %s\n", out)

	if err != nil {
		fmt.Fprintf(os.Stderr, "err: %s\n", err)
	}
}

func teardown() {
	// go.mod に indirect な依存関係が追加されてしまうので綺麗にしている
	// ref: https://github.com/golang/go/issues/26474#issuecomment-407519043
	_, err := exec.Command("go", "mod", "tidy").CombinedOutput()

	if err != nil {
		fmt.Fprintf(os.Stderr, "err: %s\n", err)
	}
}