Goのchannelのclose

wait_group.go

package main

import (
	"fmt"
	"sync"
	"time"
)

func main() {
	ch := make(chan string)
	var wg sync.WaitGroup
	wg.Add(1)

	go func() {
		//L:
		for {
			//select {
			//case v, ok := <-ch:
			//    if !ok {
			//        wg.Done()
			//        break L // ok
			//        // return // ok
			//        // break // ng WaitGroup is reused before previous Wait has returned
			//                 // https://qiita.com/cia_rana/items/a2c3e1609bd25a5c5596
			//    }
			//    time.Sleep(time.Second)
			//    fmt.Println(v)
			//}
			if v, ok := <-ch; !ok {
				wg.Done()
				break
			} else {
				time.Sleep(time.Second)
				fmt.Println(v)
			}
		}
	}()

	ch <- "=== a ==="
	ch <- "=== b ==="
	ch <- "=== c ==="
	close(ch)
	wg.Wait()
}