Go语言设计模式（五）

package main

import (
	"fmt"
	"sync"
)

func Merge(cs ...<-chan int) <-chan int {
	var wg sync.WaitGroup

	out := make(chan int)

	send := func(c <-chan int) {
		for n := range c {
			out <- n
		}
		wg.Done()
	}
	wg.Add(len(cs))

	for _, c := range cs {
		go send(c)
	}


	go func() {
		wg.Wait()
		close(out)
	}()
	return out
}

func main() {
	c := make(chan int, 2)
	d := make(chan int, 2)
	c <- 4
	c <- 5
	d <- 6
	d <- 7

	m := Merge(c, d)
	for i := range m {
		fmt.Println(i)
	}
}

package main

import (
	"fmt"
	"log"
	"net/http"
)

func isAuthorized(endpoint func(http.ResponseWriter, *http.Request)) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {

		fmt.Println("Checking to see if Authorized header set...")

		if val, ok := r.Header["Authorized"]; ok {
			fmt.Println(val)
			if val[0] == "true" {
				fmt.Println("Header is set! We can serve content!")
				endpoint(w, r)
			}
		} else {
			fmt.Println("Not Authorized!!")
			fmt.Fprintf(w, "Not Authorized!!")
		}
	})
}

func homePage(w http.ResponseWriter, r *http.Request) {
	fmt.Println("Endpoint Hit: homePage")
	fmt.Fprintf(w, "Welcome to the HomePage!")
}

func handleRequests() {

	http.Handle("/", isAuthorized(homePage))
	log.Fatal(http.ListenAndServe(":8081", nil))
}

func main() {
	handleRequests()
}