Mastering Go - Second Edition

Using defer for logging

This section will present an application of defer related to logging. The purpose of this technique is to help you organize the logging information of a function in a better way and make it more visible. The name of the Go program that will illustrate the use of the defer keyword in logging is logDefer.go and it will be presented in three parts.

The first part of logDefer.go is as follows:

package main 
 
import ( 
    "fmt" 
    "log" 
    "os" 
) 
 
var LOGFILE = "/tmp/mGo.log" 
 
func one(aLog *log.Logger) { 
    aLog.Println("-- FUNCTION one ------") 
    defer aLog.Println("-- FUNCTION one ------") 
 
    for i := 0; i < 10; i++ { 
        aLog.Println(i) 
    } 
} 

The function named one() is using defer to make sure that the second aLog.Println() call is going to ...