defer _ golang

Defer is used to ensure that a function call is performed later in a program's execution, usually for purposes of cleanup. defer is often used wheree.g.ensure and finally would be used in other languages.

package main

import (
    "fmt"
    "os"
)

func createFile(p string) *os.File {
    fmt.Println("creating")
    f, err := os.Create(p)
    if err != nil {
        panic(err)
    }
    return f
}

func writeFile(f *os.File) {
    fmt.Println("writing")
    fmt.Fprintln(f, "data")
}

func closeFile(f *os.File) {
    fmt.Println("closing")
    f.Close()
}

func main() {
    f := createFile("/tmp/defer.txt")
    defer closeFile(f)
    writeFile(f)
}

creating
writing
closing

总结 : 

　　1 : ....