How to implement these goroutines communication in below scene

Question

Given a channel slice([]chan{}),how to realize that we accept these messages from the channel array.

I consider below 2 ways, but they can solve my problem:

1. we can use "select", but the length of slice is not fixed, so the number of case is also not fixed.
2. we can traverse the slice, but it will cause block when no msg can be received.

Answer 1

You can use the reflect package to select on a dynamic number channels.

package main

import (
    "fmt"
    "reflect"
    "time"
)

func main() {
    // Create a slice of channels
    channels := make([]chan string, 5)

    // Initialize the channels
    for i := range channels {
        channels[i] = make(chan string)
    }

    // Send messages to the channels
    go func() {
        for _, ch := range channels {
            time.Sleep(time.Second)
            ch <- "hello"
        }
    }()

    // Use reflect.Select to select on a set of channels in the slice
    for {
        cases := make([]reflect.SelectCase, len(channels))
        for i, ch := range channels {
            cases[i] = reflect.SelectCase{
                Dir:  reflect.SelectRecv,
                Chan: reflect.ValueOf(ch),
            }
        }

        // Wait for a message to be received on one of the channels
        i, v, ok := reflect.Select(cases)

        if !ok {
            fmt.Println("Channel closed")
            continue
        }

        // Print the received message and the index of the channel
        fmt.Printf("Received %q from channel %d\n", v.Interface(), i)
    }
}