Question

I’ve got this piece of legacy code which I’m trying to refactor at the moment:

    public class FileManger
    {
        private IFileReader _fileReader;
        private IFileWriter _fileWriter;

        public enum Mode { Read = 1, Write = 2 };

        public void Open( Mode mode)
        {
            if (mode == Mode.Read)
            {
                _fileReader = new FileReader();
            }
            else if (mode == Mode.Write)
            {
                _fileWriter = new FileWriter();
            }
        }
    }

I need to be able to replace this piece of code with a factory method and assign the returned to a common filed.

so.. I’m trying to make it look like:

public class FileManger
{
    private IFileHandler _fileHandler;

    public enum Mode { Read = 1, Write = 2 };

    public void Open(string fileName, Mode mode)
    {
        _fileHandler = Factory.CreateFileHandler(mode);
    }
 }

The problem I have is the two original interfaces IFileReader and IFileWriter, though they are quite closer in shape to each other, they have two completely different methods string ReadLine(); and void WriteLine(string line); for which I could not find a common abstration.

Basically my refactoring goal is to make the IFileReader and IFileWriter interfaces look the same and use a common interface instead of two.

currently these interfaces look like this:

 public interface IFileReader : IDisposable
    {
        void OpenFileStream(string fileName);
        void Close();

        string ReadLine();
    }

and

public interface IFileWriter : IDisposable
    {

        void OpenFileStream(string fileName);
        void Close();

        void WriteLine(string line);
    }

could someone give me some suggestions on how I could go around achieving this?

Please let me know if you need any further clarifications, if I made it unclear to understand.

Answer 1

I can’t really see why you would like to use a common interface for such different operations, but assuming you have good reasons for that, I guess you could do something like this, where line would be read or written, depending on file mode:

public interface IFileAccessor : IDisposable
{
    void OpenFileStream(string fileName);
    void Close();
    void TransferLine(ref string line);
}