Debug log

Global debug logger; enable by setting environment variable D=t

$ D=t go run main.go

func main() {
	debug.Print("hello ...")
}

// debug logger is global to one package
var debug = log.New(ioutil.Discard, "D ", log.LstdFlags|log.Lshortfile)

func init() {
	// enable debug log if environment D=t is set
	if yes, _ := strconv.ParseBool(os.Getenv("D")); yes {
		debug.SetOutput(os.Stderr)
	}
}