defer use case

main.go

package main

import (
	"time"
	"fmt"
	"runtime"
)

type Timer struct {
	start time.Time
	defaultValue string
}

func New() *Timer {
	return &Timer{
		start: time.Now(),
		defaultValue: "{unknown}",
	}
}

func (t *Timer) End() {
	callerName := t.GetCallerName()
	if callerName == nil {
		callerName = &t.defaultValue
	}
	fmt.Printf("Execution of %v took %v", *callerName, time.Since(t.start))
}

func (t *Timer) GetCallerName() (name *string) {
	uintpt := make([]uintptr, 1)
	n := runtime.Callers(3, uintpt)
	if n == 0 {
		return
	}
	fun := runtime.FuncForPC(uintpt[0]-1)
	if fun == nil {
		return
	}
	nameTemp := fun.Name()
	name = &nameTemp
	return
}

func main() {
	defer New().End()
	fmt.Println("Sleeping!")
	time.Sleep(time.Nanosecond * 100)
	fmt.Println("Well slept!")
}