Examples of passing information to a handler via closures in Go

gistfile1.go

package main

import (
  "log"
  "net/http"
  "time"
)

func main() {
  mux := http.NewServeMux()

  mux.HandleFunc("/time", func(w http.ResponseWriter, r *http.Request) {
    timeHandler(w, r, time.RFC1123)
  })

  log.Println("Listening...")
  http.ListenAndServe(":3000", mux)
}

func timeHandler(w http.ResponseWriter, r *http.Request, format string) {
  tm := time.Now().Format(format)
  w.Write([]byte("The time is: " + tm))
}

gistfile2.go

package main

import (
  "log"
  "net/http"
  "time"
)

func main() {
  mux := http.NewServeMux()

  mux.Handle("/time", timeHandler(time.RFC1123))

  log.Println("Listening...")
  http.ListenAndServe(":3000", mux)
}

func timeHandler(format string) http.Handler {
  fn := func(w http.ResponseWriter, r *http.Request) {
    tm := time.Now().Format(format)
    w.Write([]byte("The time is: " + tm))
  }
  return http.HandlerFunc(fn)
}

gistfile3.go

package main

import (
  "log"
  "net/http"
  "time"
)

func main() {
  mux := http.NewServeMux()

  mux.Handle("/time", timeHandler(time.RFC1123))

  log.Println("Listening...")
  http.ListenAndServe(":3000", mux)
}

func timeHandler(format string) http.HandlerFunc {
  return func(w http.ResponseWriter, r *http.Request) {
    tm := time.Now().Format(format)
    w.Write([]byte("The time is: " + tm))
  }
}