So let’s put all this to use. Let’s look at an example that uses the done channel pattern, and see what benefits we might gain from switching to use of the context package. Here is a program that concurrently prints a greeting and a farewell

package.go

package main

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

func main() {
	var wg sync.WaitGroup
	done := make(chan interface{})
	defer close(done)
	wg.Add(1)
	go func() {
		defer wg.Done()
		if err := printGreeting(done); err != nil {
			fmt.Printf("%v", err)
			return
		}
	}()
	wg.Add(1)
	go func() {
		defer wg.Done()
		if err := printFarewell(done); err != nil {
			fmt.Printf("%v", err)
			return
		}
	}()
	wg.Wait()
}
func printGreeting(done <-chan interface{}) error {
	greeting, err := genGreeting(done)
	if err != nil {
		return err
	}
	fmt.Printf("%s world!\n", greeting)
	return nil
}
func printFarewell(done <-chan interface{}) error {
	farewell, err := genFarewell(done)
	if err != nil {
		return err
	}
	fmt.Printf("%s world!\n", farewell)
	return nil
}
func genGreeting(done <-chan interface{}) (string, error) {
	switch locale, err := locale(done); {
	case err != nil:
		return "", err
	case locale == "EN/US":
		return "hello", nil
	}
	return "", fmt.Errorf("unsupported locale")
}
func genFarewell(done <-chan interface{}) (string, error) {
	switch locale, err := locale(done); {
	case err != nil:
		return "", err
	case locale == "EN/US":
		return "goodbye", nil
	}
	return "", fmt.Errorf("unsupported locale")
}
func locale(done <-chan interface{}) (string, error) {
	select {
	case <-done:
		return "", fmt.Errorf("canceled")
	case <-time.After(1 * time.Minute):
	}
	return "EN/US", nil
}