<p>So, I was having trouble with this when I was writing my golang app recently. I figured that I would share it with the community. My challenge was that I was producing lots of channels and needed to poll for results in a generic way (i.e. with interfaces). Here's the full example:</p>
<pre><code>package main
import (
"fmt"
"sync"
)
func gen(nums ...int) chan interface{} {
out := make(chan interface{}, 2)
go func() {
for _, n := range nums {
out <- n
}
close(out)
}()
return out
}
func sq(in chan interface{}) chan interface{} {
out := make(chan interface{}, 2)
go func() {
for n := range in {
out <- n.(int) * n.(int)
}
close(out)
}()
return out
}
// Merging generic interface channels into a single channel
func merge(cs ...chan interface{}) chan interface{} {
var wg sync.WaitGroup
out := make(chan interface{}, 2)
output := func(c chan interface{}) {
for n := range c {
out <- n
}
wg.Done()
}
wg.Add(len(cs))
for _, c := range cs {
go output(c)
}
go func() {
wg.Wait()
close(out)
}()
return out
}
func main() {
in := gen(2, 3)
var chs []chan interface{}
chs = append(chs, sq(in))
chs = append(chs, sq(in))
for n := range merge(chs...) {
fmt.Println(n.(int))
}
}
</code></pre>
<p>And, the important parts are: </p>
<ol>
<li> Update <code>merge</code> method to use <code>interface{}</code>s instead of integers from the <a href="https://blog.golang.org/pipelines">community example</a>.</li>
<li> Use the <code>channel_array ...</code> notation for when calling merge with a list of items. It makes it <em>super</em> nice to use <code>merge</code> for both a small number of channels and for when you have a large list of channels.</li>
</ol>
<hr/>**评论：**<br/><br/>Fwippy: <pre><p>Alternately; you could provide the output channel to the <code>sq</code> function, so they all write to the same combined channel (without the merging goroutines acting as middlemen).</p></pre>
