go中defer的作用。1，在函数

// open a file  
defer file.Close()

mu.Lock()  
defer mu.Unlock()

printHeader()  
defer printFooter()

// open a database connection  
defer disconnectFromDB()

package main

import (
	"io"
	"log"
)

func func1(s string) (n int, err error) {
	defer func() {
		log.Printf("func1(%q) = %d, %v", s, n, err)
	}()
	return 7, io.EOF
}

func main() {
	func1("Go")
}