channel, goroutine, sync

gistfile1.go

package main

import (
	"fmt"
	"sync"
)

func printNumber(i int) int {
	fmt.Println(i)
	return i
}

func main() {
	wg := &sync.WaitGroup{}
	ch := make(chan int)
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			ch <- printNumber(i)
		}(i)
	}

	go func() { wg.Wait(); close(ch) }()

	for j := range ch {
		fmt.Println(j)
	}
}