How to create a function that can return nil or string value instead of the memory address?-CodePudding

My goal is to create a function that can return nil or string value.

I use *string to allow a function to return nil or string pointer.

The problem is that function return memory address instead of the string value. The easy solution is to use *.

However, I believe that is a bad practice. E.g I am comparing it with func os.Open(name string) (*os.File, error) which return os.File pointer, but I can access the variable without *.

The best practice:

func main() {
  f, _ := os.Open("/tmp/dat")

  b1 := make([]byte, 5)
  f.Read(b1) // I don't need to use *
  fmt.Println("%s", string(b1))
}

My current code which I believe is not a best practice:

func main() {
  dat, _ := ConvertPath("/tmp/dat2")
  fmt.Println(*dat) // I need to use *
}

This is the rest of the code:

func Convert(r io.Reader) (*string, error) {
    dat := "hello"
    return &dat, nil
}

func ConvertPath(path string) (*string, error) {
    f, err := os.Open(path)
    if err != nil {
        return nil, err
    }

    defer f.Close()

    return Convert(f)
}

CodePudding user response：

To summarize the various comments:

You can simply return an empty string instead of a pointer.

func Convert(r io.Reader) (string, error) {
    dat := "hello"
    return dat, nil
}

func ConvertPath(path string) (string, error) {
    f, err := os.Open(path)
    if err != nil {
        return "", err
    }
    defer f.Close()

    return Convert(f)
}

func main() {
  dat, err := ConvertPath("/tmp/dat2")
  if err != nil {
    panic(err)
  }
  fmt.Println(dat)
}