FormatWith class

FormatWith.cs

public static class FormatWith
{
    public static string FormatString(string format, object source)
    {
        return FormatString(format, null, source);
    }

    public static string FormatString(string format, IFormatProvider provider, object source)
    {
        if (format == null)
        {
            throw new ArgumentNullException("format");
        }

        var r = new Regex(
            @"(?<start>\{)+(?<property>[\w\.\[\]]+)(?<format>:[^}]+)?(?<end>\})+",
            RegexOptions.Compiled | RegexOptions.CultureInvariant | RegexOptions.IgnoreCase);

        var values = new List<object>();
        var rewrittenFormat = r.Replace(
            format,
            delegate(Match m)
            {
                var startGroup = m.Groups["start"];
                var propertyGroup = m.Groups["property"];
                var formatGroup = m.Groups["format"];
                var endGroup = m.Groups["end"];

                values.Add((propertyGroup.Value == "0") ? source : DataBinder.Eval(source, propertyGroup.Value));

                return new string('{', startGroup.Captures.Count) + (values.Count - 1) + formatGroup.Value +
                       new string('}', endGroup.Captures.Count);
            });

        return string.Format(provider, rewrittenFormat, values.ToArray());
    }
}