代码

package main 

import (
    "log"
    "os"
)

/*
2016/10/20 13:25:42 Hello, 5 + 3 =  8
[bar]2016/10/20 13:25:42 test.go:29: Hello, world!
[bar]2016/10/20 13:25:42 test.go:30: Hello,  world!
[bar]2016/10/20 13:25:42 test.go:31: 5 + 3 = 8
[bar]2016/10/20 13:25:42 test.go:33: Program will exit from here.
exit status 1
*/
func main() {
    foo()
    bar()
}

func foo() {
    log.Println("Hello, 5 + 3 = ", 5 + 3)
}

func bar() {
    logger := log.New(os.Stdout, "[bar]", log.Lshortfile | log.Ldate | log.Ltime)
    logger.Println("Hello, world!")
    logger.Println("Hello, ", "world!")
    logger.Printf("5 + 3 = %d\n", 5 + 3)

    logger.Fatal("Program will exit from here.")
    logger.Println("Unreachable code.")
}