正则表达式学习，使用.NET framework api

public static string Process(string input)
        {
            Regex r = new Regex(@"\$\{(?<custId>\d+):(?<attrib>\w+)}");
            return r.Replace(input, Evaluate);
        }

        static string Evaluate(Match match)
        {
            Customer c = new Customer { Name = "同志们", Ssn = "123", Company = "公司" };
            switch (match.Groups["attrib"].Value)
            {
                case "name":
                    return c.Name;
                case "ssn":
                    return c.Ssn;
                case "company":
                    return c.Company;
                default:
                    throw new Exception();
                    break;
            }
        }

        class Customer
        {
            public string Name { get; set; }
            public string Ssn { get; set; }
            public string Company { get; set; }