摘自 从并发模型看 Go 的语言设计 | 腾讯技术工程，更新中…
Go 语言中
channel的<-：左读右写
1. 阶乘计算
package main
import "fmt"
const limit = 5
func main() {
fact := MakeFactFunc()
for i := 0; i < limit; i++ {
fmt.Println(fact(i))
}
}
// 阶乘计算的实体
func FactCalc(in <-chan int, out chan<- int) {
var subIn, subOut chan int
for {
n := <-in
if n == 0 {
out <- 1
} else {
if subIn == nil {
subIn, subOut = make(chan int), make(chan int)
go FactCalc(subIn, subOut)
}
subIn <- n - 1
r := <-subOut
out <- n * r
}
}
}
// 包装一个阶乘计算函数
func MakeFactFunc() func(int) int {
in, out := make(chan int), make(chan int)
go FactCalc(in, out)
return func(x int) int {
in <- x
return <-out
}
}
------
1
1
2
6
24
Process finished with exit code 0
2. 筛法求素数
package main
import "fmt"
func main() {
primes := make(chan int)
go PrimeSieve(primes)
for i := 0; i < 5; i++ {
fmt.Println(<-primes)
}
}
func Counter(out chan<- int) {
for i := 2; ; i++ {
out <- i
}
}
func PrimeFilter(prime int, in <-chan int, out chan<- int) {
for {
i := <-in
if i%prime != 0 {
out <- i
}
}
}
func PrimeSieve(out chan<- int) {
c := make(chan int)
go Counter(c)
for {
prime := <-c
out <- prime
newC := make(chan int)
go PrimeFilter(prime, c, newC)
c = newC
}
}
------
2
3
5
7
11
Process finished with exit code 0
