Identity check in Go

//
// Demonstrate identities as used by the request-reply pattern. Run this
// program by itself.
//

package main

import (
zmq "github.com/alecthomas/gozmq"
"fmt"
)

func dump(sink zmq.Socket) {
parts, err := sink.RecvMultipart(0)
if err != nil { fmt.Println(err) }
for _, msgdata := range parts {
is_text := true
fmt.Printf("[%03d] ", len(msgdata))
for _, char := range msgdata {
if char < 32 || char > 127 {
is_text = false
}
}
if is_text {
fmt.Printf("%s\n", msgdata)
} else {
fmt.Printf("%X\n", msgdata)
}
}
}

func main() {
context, _ := zmq.NewContext()
defer context.Close()

sink, err := context.NewSocket(zmq.ROUTER)
if err != nil { print(err) }
defer sink.Close()
sink.Bind("inproc://example")

// First allow 0MQ to set the identity
anonymous, err := context.NewSocket(zmq.REQ)
defer anonymous.Close()
if err != nil { fmt.Println(err) }
anonymous.Connect("inproc://example")
err = anonymous.Send([]byte("ROUTER uses a generated UUID"), 0)
if err != nil { fmt.Println(err) }

dump(sink)

// Then set the identity ourself
identified, err := context.NewSocket(zmq.REQ)
if err != nil { print(err) }
defer identified.Close()
identified.SetSockOptString(zmq.IDENTITY, "Hello")
identified.Connect("inproc://example")
identified.Send([]byte("ROUTER socket uses REQ's socket identity"), zmq.NOBLOCK)

dump(sink)
}