Golang自定义错误接口实现与调用实践

type MyError struct {
    Code    int
    Msg     string
    Time    time.Time
}

func (e *MyError) Error() string {
    return fmt.Sprintf("[%d] %s at %v", e.Code, e.Msg, e.Time)
}

func NewMyError(code int, msg string) *MyError {
    return &MyError{
        Code: code,
        Msg:  msg,
        Time: time.Now(),
    }
}

err := NewMyError(404, "resource not found")
if err != nil {
    log.Println(err)
}

type NetworkError struct {
    Op      string
    ErrMsg  string
}

func (e *NetworkError) Error() string {
    return "network error during " + e.Op + ": " + e.ErrMsg
}

func CallAPI() error {
    // 模拟失败
    return &NetworkError{Op: "POST", ErrMsg: "connection timeout"}
}

err := CallAPI()
if netErr, ok := err.(*NetworkError); ok {
    if netErr.Op == "POST" {
        // 可重试操作
        retry()
    }
}

func ReadConfig() error {
    file, err := os.Open("config.json")
    if err != nil {
        return fmt.Errorf("failed to open config: %w", err)
    }
    defer file.Close()

    // ...
    return nil
}

err := ReadConfig()
var pathErr *os.PathError
if errors.As(err, &pathErr) {
    log.Printf("Path error: %v", pathErr.Path)
}