为什么这些具有相同功能的方法写的不同？

Question

func (log Logger) Warn(arg0 interface{}, args ...interface{}) error {
const (
    lvl = WARNING
)
var msg string
switch first := arg0.(type) {
case string:
    // Use the string as a format string
    msg = fmt.Sprintf(first, args...)
case func() string:
    // Log the closure (no other arguments used)
    msg = first()
default:
    // Build a format string so that it will be similar to Sprint
    msg = fmt.Sprintf(fmt.Sprint(first)+strings.Repeat(" %v", len(args)), args...)
}
log.intLogf(lvl, msg)
return errors.New(msg)
}

func (log Logger) Info(arg0 interface{}, args ...interface{}) {
const (
    lvl = INFO
)
switch first := arg0.(type) {
case string:
    // Use the string as a format string
    log.intLogf(lvl, first, args...)
case func() string:
    // Log the closure (no other arguments used)
    log.intLogc(lvl, first)
default:
    // Build a format string so that it will be similar to Sprint
    log.intLogf(lvl, fmt.Sprint(arg0)+strings.Repeat(" %v", len(args)), args...)
}

}

These two functions are from log4go library's source code,I don't know why Warn(in fact all level higher than Warn) is different from Info, Why does Warn function Sprintf the msg first while Info passes all args to the iniLogf function to handle the logging? Is it because the closure may be leave out if the process aborted at that timing?

Answer 1

The most likely explanation is that due to the fact that Logger.Warn method returns an error value, it was refactored to at first save the value it needs to log into variable msg and then log it separately as well as return it as the error. Logger.Info, at the same time, logs the message as soon as it is possible because it is not required to return the message. This seems to be the only difference in the way these functions work.