learnFromBradfitz.go

package main

import (
	"fmt"
)

var serverMap = map[int32]string{1: "server1", 2: "server2", 3: "server3"}

func main()  {
	var id int32 = 1

	withId(id, func(s string) {
		fmt.Printf("Get server %s by ID %d, then todo ...\n", s, id)
	})

	id = 2
	withId(id, func(s string) {
		fmt.Printf("Get server %s by ID %d, then todo ...\n", s, id)
	})

	id = 4
	withId(id, func(s string) {
		fmt.Printf("Get server %s by ID %d, then todo ...\n", s, id)
	})
}

func withId(id int32, fn func(string)) {
	if server, ok := serverMap[id]; ok {
		fn(server)
	} else {
		fmt.Println("Server not found.")
	}
}