What are some examples of Go interfaces?

Question

I found an interesting blog post about Go. I am trying to understand the concept of interfaces, but I find it very hard to do so from the code fragment in the blog post, and nearly impossible from the language specification. Can anyone point out a simple example of Go's interfaces in a working program?

Answer 1

The base concept of interfaces in Go, is that any object implementing a method defined an interface, can be a part of that interface.

The best example is the Writer interface. Rob Pike has an example of this in his intro speech at Google Tech Talk ( http://www.youtube.com/watch?v=rKnDgT73v8s ) - scroll to 33:25 into the speech for his explanation.

Answer 2

It's a work-in-progress learning exercise, and certainly a poor example of good style, but here you go (spec).

Additionally, as a more exotic example, I made a post on the go-nuts mailing list regarding using interface{} for building functions that work with anonymous data (in this case, a "ternary operation" function):

package main
import "fmt";
func Tern(exp bool, a interface{}, b interface{}) (interface{}) {
    if exp { return a }
    return b
}
func main() {
    a := 7; b := 1;
    result := Tern(a > b, a, b);
    fmt.Printf("%d\n", result);
}