promise

A simple, fast implementation of a promise in Go.

Example

// do something that takes 10 seconds to return
func do() (string, error) {
    time.Sleep(10 * time.Second)
    return "result", nil
}

func doAsync() *promise.Promise {
    p := promise.NewPromise()

    // Start a goroutine that completes the promise
    // once the result is returned.
    go func() {
        v, err := do()
        if err != nil {
            p.CompleteWithError(err)
            return
        }
        p.Complete(v)
    }()
    return p
}

func main() {
    p := doAsync()

    // Calling 'Get' blocks until the result is ready.
    v, err := p.Get()
    if err != nil {
        panic(err)
    }
    if result, ok := v.(string); ok {
        fmt.Printf("Promise result: %s", result)
    }
}