Type agnostic channels in go

interface go channel
ben lemasurier picture ben lemasurier · Feb 28, 2014 · Viewed 17.4k times · Source

I'm still sort of wrapping my head around interfaces within golang. Is it possible to send multiple different types over a single, "generic" channel?

Here's a very simple example: http://play.golang.org/p/7p2Bd6b0QT.

Answer

cnicutar picture cnicutar · Feb 28, 2014

Yes, it's possible. For example in your code you could just use:

greet: make(chan pet)

And then you would be able to send seamlessly anything that implements type pet interface.

If you want to send something completely generic you can use a chan interface{} and then use reflect to find out what it is when you receive something.

A dumb - and probably not idiomatic - example:

ch := make(chan interface{})

go func() {
    select {
    case p := <-ch:
        fmt.Printf("Received a %q", reflect.TypeOf(p).Name())
    }
}() 
ch <- "this is it"

As BurntSushi5 points out, a type switch is better:

p := <-ch
switch p := p.(type) {
case string:
    fmt.Printf("Got a string %q", p)
default:
    fmt.Printf("Type of p is %T. Value %v", p, p)
}

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