expvar package demo for Gunosy.go #3.

demo.go

package main

import (
        "expvar"
        "io"
        "net/http"
)

var numCalls = expvar.NewInt("num_calls")

func helloHandler(w http.ResponseWriter, req *http.Request) {
        numCalls.Add(1)
        io.WriteString(w, "Hello Gopher!\n")
}

func main() {
        http.HandleFunc("/", helloHandler)
        http.ListenAndServe(":8080", nil)
}