英文:
Is it possible to access channels ch1, ch2 using `select` in Golang?
问题
我正在尝试调试这段代码，但卡在这里。我想要访问ch1和ch2，但发现没有打印任何内容。
package mainimport ("fmt")type degen struct {i, j string}func (x degen) CVIO(ch1, ch2 chan string, quit chan int, m, n string) {for {select {case ch1 <- m:fmt.Println(x.i)case ch2 <- n:fmt.Println("ok")case <-quit:fmt.Println("quit")return}}}func main() {ch1 := make(chan string)ch2 := make(chan string)quit := make(chan int)x := degen{"goosebump", "ok"}go x.CVIO(ch1, ch2, quit, "goosebump", "ok")}
期望的结果：
它应该打印即将产生的通道数据。
英文:
I was trying to debug this code but am stuck here. I wanted to access ch1, ch2 but found printed nothing.
package mainimport ("fmt")type degen struct {i, j string}func (x degen) CVIO(ch1, ch2 chan string, quit chan int, m, n string) {for {select {case ch1 <- m:fmt.Println(x.i)case ch2 <- n:fmt.Println("ok")case <-quit:fmt.Println("quit")return}}}func main() {ch1 := make(chan string)ch2 := make(chan string)quit := make(chan int)x := degen{"goosebump", "ok"}go x.CVIO(ch1, ch2, quit, "goosebump", "ok")}
Desired:
It should print the channel data as to be produced.
答案1
得分: 3
你的代码的预期功能并不是很清楚：
main()函数在结束时没有等待 go 协程退出（循环可能根本不会运行）。- 在
select语句中，发送操作无法进行，因为没有接收者（参考 规范 - "如果容量为零或不存在，则通道是无缓冲的，只有在发送方和接收方都准备好时通信才会成功。"）。 - 没有向
quit通道发送任何内容。
我怀疑以下代码（playground）可能会实现你的预期功能。
package mainimport ("fmt""sync")type degen struct {i, j string}func (x degen) CVIO(ch1, ch2 chan string, quit chan int, m, n string) {for {select {case ch1 <- m:fmt.Println(x.i)case ch2 <- n:fmt.Println("ok")case <-quit:fmt.Println("quit")return}}}func main() {ch1 := make(chan string)ch2 := make(chan string)quit := make(chan int)x := degen{"goosebump", "ok"}var wg sync.WaitGroupwg.Add(1)go func() {x.CVIO(ch1, ch2, quit, "goosebump", "ok")wg.Done()}()<-ch1 // 从 CH1 接收（允许 go 协程中的 "ch1 <- m" 继续执行）<-ch2 // 从 CH2 接收（允许 go 协程中的 "ch2 <- n" 继续执行）quit <- 1wg.Wait() // 等待 CVIO 结束（由于上述发送操作，它应该会结束）}
希望对你有帮助！
英文:
Its not really clear what you expect your code to do:
main()ends without waiting for the go routine to exit (its quite possible it the loop will not run at all).- in the
selectthe sends will not proceed because there is no receiver (spec - "if the capacity is zero or absent, the channel is unbuffered and communication succeeds only when both a sender and receiver are ready."). - Nothing is sent to the
quitchannel.
I suspect that the following (playground) might do what you were expecting.
package mainimport ("fmt""sync")type degen struct {i, j string}func (x degen) CVIO(ch1, ch2 chan string, quit chan int, m, n string) {for {select {case ch1 <- m:fmt.Println(x.i)case ch2 <- n:fmt.Println("ok")case <-quit:fmt.Println("quit")return}}}func main() {ch1 := make(chan string)ch2 := make(chan string)quit := make(chan int)x := degen{"goosebump", "ok"}var wg sync.WaitGroupwg.Add(1)go func() {x.CVIO(ch1, ch2, quit, "goosebump", "ok")wg.Done()}()<-ch1 // Receive from CH1 (allowing "ch1 <- m" in go routine to proceed)<-ch2 // Receive from CH2 (allowing "ch2 <- n" in go routine to proceed)quit <- 1wg.Wait() // Wait for CVIO to end (which it should do due to above send)}
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