Better enums in C# for DDD ... based on Jimmy Bogards Enumeration class

Enumeration.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Reflection;

[Serializable]
[DebuggerDisplay("{DisplayName} - {Value}")]
public abstract class Enumeration<TEnumeration, TValue> : IComparable<TEnumeration>, IEquatable<TEnumeration>
    where TEnumeration : Enumeration<TEnumeration, TValue>
    where TValue : IComparable
{
    private static readonly TEnumeration[] Enumerations = GetEnumerations();

    private readonly string displayName;
    private readonly TValue value;

    protected Enumeration(TValue value, string displayName)
    {
        this.value = value;
        this.displayName = displayName;
    }

    public TValue Value
    {
        get { return value; }
    }

    public string DisplayName
    {
        get { return displayName; }
    }

    public static TEnumeration[] GetAll()
    {
        return Enumerations;
    }

    public static TEnumeration FromValue(TValue value)
    {
        return Parse(value, "value", item => item.Value.Equals(value));
    }

    public static TEnumeration Parse(string displayName)
    {
        return Parse(displayName, "display name", item => item.DisplayName == displayName);
    }

    public static bool TryParse(TValue value, out TEnumeration result)
    {
        return TryParse(x => x.Value.Equals(value), out result);
    }

    public static bool TryParse(string displayName, out TEnumeration result)
    {
        return TryParse(x => x.DisplayName == displayName, out result);
    }

    public int CompareTo(TEnumeration other)
    {
        return Value.CompareTo(other.Value);
    }

    public override sealed string ToString()
    {
        return DisplayName;
    }

    public override bool Equals(object obj)
    {
        return Equals(obj as TEnumeration);
    }

    public bool Equals(TEnumeration other)
    {
        return other != null && Value.Equals(other.Value);
    }

    public override int GetHashCode()
    {
        return Value.GetHashCode();
    }

    private static bool TryParse(Func<TEnumeration, bool> predicate, out TEnumeration result)
    {
        result = GetAll().FirstOrDefault(predicate);

        return result != null;
    }

    private static TEnumeration[] GetEnumerations()
    {
        var enumerationType = typeof(TEnumeration);

        return enumerationType
            .GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.DeclaredOnly)
            .Where(info => enumerationType.IsAssignableFrom(info.FieldType))
            .Select(info => info.GetValue(null))
            .Cast<TEnumeration>()
            .ToArray();
    }

    private static TEnumeration Parse(object value, string description, Func<TEnumeration, bool> predicate)
    {
        TEnumeration result;

        if (!TryParse(predicate, out result))
        {
            var message = string.Format("'{0}' is not a valid {1} in {2}", value, description, typeof(TEnumeration));
            throw new ArgumentException(message, "value");
        }

        return result;
    }
}

Example.EmailType.cs

public abstract class EmailType : Enumeration<EmailType, int>
{
    public static readonly EmailType AnythingElse = new AnythingElseType();
    public static readonly EmailType SpecialEmail = new SpecialEmailType();

    protected EmailType(int value, string displayName) : base(value, displayName)
    {
    }

    protected static string SendGridSmtp
    {
        get { return "smtp.sendgrid.net"; }
    }

    protected static int SendGridPort
    {
        get { return 587; }
    }

    public abstract SmtpSettings GetSmtpSettings();

    private class AnythingElseType : EmailType
    {
        public AnythingElseType() : base(0, "AnythingElse")
        {
        }

        public override SmtpSettings GetSmtpSettings()
        {
            return new SmtpSettings
                {
                    Port = SendGridPort,
                    Server = SendGridSmtp,
                    UseSsl = true,
                    Username = "[email protected]",
                    Password = "somePassword"
                };
        }
    }

    private class SpecialEmailType : EmailType
    {
        public SpecialEmailType() : base(1, "SpecialEmail")
        {
        }

        public override SmtpSettings GetSmtpSettings()
        {
            return new SmtpSettings
                {
                    Port = SendGridPort,
                    Server = SendGridSmtp,
                    UseSsl = true,
                    Username = "[email protected]",
                    Password = "anotherPassword"
                };
        }
    }
}

Example.Main.cs

public void Main()
{
    var emailType = EmailType.SpecialEmail;
    var mailMessage = new MailMessage("[email protected]", "[email protected]", "Test", "This is a test email");
    
    SendMail(emailType, mailMessage);
}

public void SendMail(EmailType emailType, MailMessage mailMessage)
{
    using(var smtpClient = emailType.GetSmtpSettings().CreateSmtpClient())
    {
        smtpClient.Send(mailMessage);
    }
}

Example.SmtpSettings.cs

using System.Net;
using System.Net.Mail;

public class SmtpSettings
{
    public string Server { get; set; }

    public string Username { get; set; }

    public string Password { get; set; }

    public bool UseSsl { get; set; }

    public int Port { get; set; }

    public SmtpClient CreateSmtpClient()
    {
        return new SmtpClient(Server, Port)
                {
                    Credentials = new NetworkCredential(Username, Password),
                    EnableSsl = UseSsl,
                    DeliveryMethod = SmtpDeliveryMethod.Network,
                };
    }
}

well played!

Cool Idea Thanks for this