Go directional channel (one-way channel)

A directional channel is a channel that can only send or receive data.

---

A two-way channel looks like this:

 package main
import "fmt"
func main() {
    ch1 := make(chan string)
    //建立一个chanel 通知一下 在子协程没结束之前 主协程不要结束
    done := make(chan bool)
    go sendData(ch1, done)
    data := <-ch1
    fmt.Println("子协程中传来的数据： ", data)
    ch1 <- "that is rain"
    <-done
    fmt.Println("main finished")
}
func sendData(ch1 chan string, done chan bool) {
    ch1 <- "this is bill"
    data := <-ch1
    fmt.Println("主协程传来的数据", data)
    //这个表示在子的协程结束的时候 再传递一个 bool 告诉 主协程 子协程已经执行完毕，否则主协程先不要结束
    done <- true
}

The result of running is this:

 子协程中传来的数据：  this is bill
主协程传来的数据 that is rain
main finished

---

The above is the writing method of the two-way channel. The following is a description of the one-way channel:

 package main

import "fmt"

func main() {
    //双向chanel
    ch1 := make(chan int)
    //单向：只能写
    //ch2 := make(chan<- int)
    ////单向：只能读
    //ch3 := make(<-chan int)

    go writes(ch1)
    //go writes(ch2)
    data := <-ch1
    fmt.Println("the data from writes is : ", data)
}

func writes(ch chan<- int) {
    ch <- 100
    fmt.Println("writing completed")
}

For the so-called one-way channel, at the beginning of creation, a two-way channel is usually created, but only in the function (for example, the writes here are set to write-only).

Reference: bilibili