1、单向channel特点
package main //"fmt" func main() {
//创建一个channel, 双向的
ch := make(chan int) //双向channel能隐式转换为单向channel
var writeCh chan<- int = ch //只能写,不能读
var readCh <-chan int = ch //只能读,不能写 writeCh <- 666 //写
//<-writeCh //err, invalid operation: <-writeCh (receive from send-only type chan<- int) <-readCh //读
//readCh <- 666 //写, err, invalid operation: readCh <- 666 (send to receive-only type <-chan int) //单向无法转换为双向
//var ch2 chan int = writeCh //cannot use writeCh (type chan<- int) as type chan int in assignment }