There is a well known technique within black-hat SEO called content spinning. Content spinning involves writing an article using a specific syntax which allows a text processor to generate random variations. These variations can then be used for multiple purposes without fear of being labelled as duplicate content.

I was searching for a C# algorithm which I could re-purpose into a nAnt script, but a few searches on the internet gave no results. I found a python version which seemed good enough, so I rewrote it for C#.

public static class Spinner
{
    private readonly static Random Randomizer = new Random();

    public static string Spin(string content)
    {
        const char OPEN_BRACE = '{';
        const char CLOSE_BRACE = '}';
        const char DELIMITER = '|';

        var start = content.IndexOf(OPEN_BRACE);
        var end = content.IndexOf(CLOSE_BRACE);

        if (start == -1 && end == -1 || start == -1 || end < start)
        {
            return content;
        }

        if (end == -1)
        {
            throw new ArgumentException("Unbalanced brace.");
        }

        var substring = content.Substring(start + 1, content.Length - (start + 1));
        var rest = Spin(substring);
        end = rest.IndexOf(CLOSE_BRACE);

        if (end == -1)
        {
            throw new ArgumentException("Unbalanced brace.");
        }

        var splits = rest.Substring(0, end).Split(DELIMITER);
        var item = splits[Randomizer.Next(0, splits.Length)];
        return content.Substring(0, start) + item + Spin(rest.Substring(end + 1, rest.Length - (end + 1)));
    }
}

Usage:

Spinner.Spin("{Hi|Hello|Good morning}, my name is {Matt|Bob} and I {certainly |might |should |}have {something {important|special} to {say|eat|share}|a favorite {toy|book|poem|song}}.");

There seems to be a lot of noise around CQRS and DDDD these days:

• Mark Nijhof has uploaded a DDDD sample using a CQRS approach
• Greg Young has put up a simplest possible CQRS implementation on GitHub.
• NCQRS - a framework for enabling development of CQRS-based architectures is gaining some momentum. The getting started screencast was great.

Thycotic have put up a Code Challenge.

Below is my heavily LINQ-oriented solution:

public interface IConverter
{
    string Convert(int number);
    int Convert(string number);
    string ConvertUsing(IConverter convertor, string number);
}

public abstract class ConverterBase : IConverter
{
    protected abstract string Chars { get; }

    public string Convert(int number)
    {
        return this.Encode(number)
                   .Aggregate(string.Empty, (s, c) => s + c);
    }

    public int Convert(string number)
    {
        return number.Reverse()
                     .Select((c, i) => Chars.IndexOf(c) * (int)Math.Pow(this.Chars.Length, i))
                     .Sum();
    }

    public string ConvertUsing(IConverter convertor, string number)
    {
        return convertor.Convert(this.Convert(number));
    }

    private IEnumerable<char> Encode(int number)
    {
        var remainder = number % this.Chars.Length;
        if (number - remainder > 0)
        {
            foreach (var power in this.Encode((number - remainder) / this.Chars.Length))
            {
                yield return power;
            }
        }
        yield return this.Chars[remainder];
    }
}

public class Converter : ConverterBase
{
    protected override string Chars
    {
        get
        {
            return "0123456789xyz";
        }
    }
}

public class HexConverter : ConverterBase
{
    protected override string Chars
    {
        get
        {
            return "0123456789abcdef";
        }
    }
}

public class BinaryConverter : ConverterBase
{
    protected override string Chars
    {
        get
        {
            return "01";
        }
    }
}

public class OctalConverter : ConverterBase
{
    protected override string Chars
    {
        get
        {
            return "01234567";
        }
    }
}

Note: The code doesn't handle negative inputs or exceptions.

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