【Go 语言社区】www.golangweb.com通过工信部审核，正式挂牌社区域名

package main


import(

   "os"

   "sync"

   "time"

)



var (

   myFile *os.File

   myLock sync.Mutex

)



func Open(file string) error {

   myLock.Lock()

   defer myLock.Unlock()

   f, err := os.Open(file)

   if err != nil {

       return err

   }

   myFile = f

   return nil

}



func main() {

   defer func() {

       myLock.Lock()

       defer myLock.Unlock()

       if myFile != nil {

           myFile.Close()

           myFile = nil

       }

   }()

   time.Sleep(time.Second * 3)

}