Go语言defer的一些神奇规则示例详解

package main
import (
	"fmt"
)
/**
 * @Author: Jason Pang
 * @Description: 快照
 */
func deferFuncParameter1() {
	var aInt = 1
	defer fmt.Println(aInt)
	aInt = 2
	return
}
/**
 * @Author: Jason Pang
 * @Description: 快照
 */
func deferFuncParameter2() {
	var aInt = 1
	defer func(t int) {
		fmt.Println(t)
	}(aInt)
	aInt = 2
	return
}
/**
 * @Author: Jason Pang
 * @Description: 动态
 */
func deferFuncParameter3() {
	var aInt = 1
	defer func() {
		fmt.Println(aInt)
	}()
	aInt = 2
	return
}
/**
 * @Author: Jason Pang
 * @Description: 影响返回值
 * @return ret
 */
func deferFuncReturn1() (ret int) {
	ret = 10
	defer func() {
		ret++
		fmt.Println("-----", ret)
	}()
	return 2
}
/**
 * @Author: Jason Pang
 * @Description: 不影响返回值
 * @return ret
 */
func deferFuncReturn2() (ret int) {
	ret = 10
	defer func(ret int) {
		ret++
		fmt.Println("-----", ret)
	}(ret)
	return 2
}
/**
 * @Author: Jason Pang
 * @Description: defer顺序
 */
func deferFuncSeq1() {
	var aInt = 1
	defer fmt.Println(aInt)
	aInt = 2
	defer fmt.Println(aInt)
	return
}
func main() {
	fmt.Println("快照")
	deferFuncParameter1()
	deferFuncParameter2()
	deferFuncParameter3()
	fmt.Println("返回值")
	fmt.Println(deferFuncReturn1())
	fmt.Println(deferFuncReturn2())
	fmt.Println("执行顺序")
	deferFuncSeq1()
}

func deferFuncParameter1() {
	var aInt = 1
	defer fmt.Println(aInt)
	aInt = 2
	return
}
func deferFuncParameter2() {
	var aInt = 1
	defer func(t int) {
		fmt.Println(t)
	}(aInt)
	aInt = 2
	return
}

func deferFuncParameter3() {
	var aInt = 1
	defer func() {
		fmt.Println(aInt)
	}()
	aInt = 2
	return
}

func deferFuncReturn1() (ret int) {
	ret = 10
	defer func() {
		ret++
		fmt.Println("-----", ret)
	}()
	return 2
}

func  Update() (resp *baseinfo.Resp, err error) {
	//开启事务
	panicked := true
	tx, err := db.TXBegin()
	if err != nil {
		return resp, nil
	}
	defer func() {
		if panicked || err != nil {
			tx.Rollback()
		}
	}()
	//更新
	err = h.update(shopId, tx)
	if err != nil {//失败返回
		return resp, nil
	}
	panicked = false
	err = tx.Commit().Error
	if err != nil { //失败返回
		return resp, nil
	}
	return
}