Fähigkeiten zur Fehlerbehandlung in Golang-Funktionen

func f() error {
    return errors.New("some error")
}

func main() {
    err := f()
    if err != nil {
        fmt.Println(err.Error()) // 输出: some error
    }
}

func f() error {
    return fmt.Errorf("cannot open file: %s", filename)
}

func main() {
    err := f()
    if err != nil {
        fmt.Println("Error:", err) // 输出: Error: cannot open file: filename
    }
}

func f() error {
    err := os.OpenFile("filename", os.O_RDWR, 0666) // 可能抛出错误
    return errors.Wrap(err, "failed to open file")
}

func main() {
    err := f()
    if err != nil {
        fmt.Println("Error:", err) // 输出: Error: failed to open file: filename
                                    // 同时包含底层错误信息
    }
}

type FileOpenError struct {
    path string
    err  error
}

func (e *FileOpenError) Error() string {
    return fmt.Sprintf("cannot open file: %s: %v", e.path, e.err)
}

func f() error {
    err := os.OpenFile("filename", os.O_RDWR, 0666)
    if err != nil {
        return &FileOpenError{path: "filename", err: err}
    }
    return nil
}

func main() {
    err := f()
    if err != nil {
        if casted, ok := err.(*FileOpenError); ok {
            fmt.Println("Error:", casted.Error()) // 输出: cannot open file: filename: open filename: permission denied
        }
    }
}

func apiCall() error {
    resp, err := http.Get("https://example.com/api")
    if err != nil {
        return errors.Wrap(err, "failed to make API call")
    }
    defer resp.Body.Close()
    ... // 处理响应
}

func main() {
    err := apiCall()
    if err != nil {
        fmt.Println("Error:", err) // 输出: Error: failed to make API call: Get https://example.com/api: dial tcp: lookup example.com on 8.8.8.8:53: no such host
    }
}