ExtendedStringBuilder

public class ExtendedStringBuilder
{
    private StringBuilder _stringBuilder;

    public string CurrentString
    {
        get { return _stringBuilder.ToString(); }
    }

    public int Length
    {
        get { return _stringBuilder.Length; }
    }

    public ExtendedStringBuilder()
    {
        _stringBuilder = new StringBuilder();
    }

    public ExtendedStringBuilder(int capacity)
    {
        _stringBuilder = new StringBuilder(capacity);
    }

    public ExtendedStringBuilder Append(object o)
    {
        if (o is char)
            _stringBuilder.Append((char)o);
        else if ((o as string) != null)
            _stringBuilder.Append((string)o);
        else
            _stringBuilder.Append(o);
        return this;
    }

    public static ExtendedStringBuilder operator +(ExtendedStringBuilder sb, object o)
    {
        if (o is char)
            return sb.Append((char)o);
        if ((o as string) != null)
            sb.Append((string)o);
        return sb.Append(o);
    }

    public static implicit operator string(ExtendedStringBuilder sb)
    {
        return sb.CurrentString;
    }

    public static implicit operator ExtendedStringBuilder(string s)
    {
        return new ExtendedStringBuilder().Append(s);
    }

    public override string ToString()
    {
        return CurrentString;
    }

    public string ToString(int startIndex, int length)
    {
        return _stringBuilder.ToString(startIndex, length);
    }
}