channel directions _ golang

When using channels as function parameters, you can specify if a channel is meant to only send or receive values. This specificity increases the type-safety of the program

package main

import (
    "fmt"
)

func ping(pings chan<- string, message string) {
    pings <- message
}

func pong(pings <-chan string, pongs chan<- string) {
    msg := <-pings
    pongs <- msg
}

func main() {
    pings := make(chan string, 1)
    pongs := make(chan string, 1)
    ping(pings, "passed message")
    pong(pings, pongs)
    fmt.Println(<-pongs)
}

总结 

　　1 : ....