Single-line function timing in Go

main.go

// based on https://twitter.com/francesc/status/602606902187458560

package main

import (
	"log"
	"time"
)

func main() {
	runTask("my-task")
}

func whenDone(msg string, args  ...interface{}) func() {
	start := time.Now()
	return func() {
		log.Printf(msg, append(args, time.Since(start))...)
	}
	
}

func runTask(name string) {
	defer whenDone("Done running '%v'. Total time: %v.", name)()
	
	log.Printf("Start running '%v' ...", name)
	time.Sleep(time.Second)
}