The use of Go language-defer

Defer

Automatically executes code when the function exits, regardless of whether the program has an exception

Practical Example 1

package mainimport (    "fmt")func main() {    defer func() {        fmt.Println("main defer")    }()    if err := test0(); err != nil {        fmt.Println(err.Error())        return    }    if err := test1(); err != nil {        fmt.Println(err.Error())        return    }}func test0() error {    return nil}func test1() error {    return nil}

Run results

    main defer

Example 2

package mainimport (    "fmt"    "errors")func main() {    defer func() {        fmt.Println("main defer")    }()    if err := test0(); err != nil {        fmt.Println(err.Error())        return    }    if err := test1(); err != nil {        fmt.Println(err.Error())        return    }}func test0() error {    return errors.New("test0 error") }func test1() error {    return nil}

Run results

test0 errormain defer

Example 3

package mainimport (    "fmt"    "errors")func main() {    defer func() {        fmt.Println("main defer")    }()    if err := test0(); err != nil {        fmt.Println(err.Error())        return    }    if err := test1(); err != nil {        fmt.Println(err.Error())        return    }}func test0() error {    return nil}func test1() error {    return errors.New("test1 error") }

Run results

test1 errormain defer

Example 4

package mainimport (    "fmt"    "errors")func main() {    defer func() {        fmt.Println("main defer0")    }()    defer func() {        fmt.Println("main defer1")    }()    if err := test0(); err != nil {        fmt.Println(err.Error())        return    }    if err := test1(); err != nil {        fmt.Println(err.Error())        return    }}func test0() error {    defer func() {        fmt.Println("test0 defer")    }()    return nil}func test1() error {    defer func() {        fmt.Println("test1 defer")    }()    return errors.New("test1 error") }

Run results

test0 defertest1 defertest1 errormain defer1main defer0

The use of Go language-defer