Extending enums in c#

Question

in java im used to extending enum values or overriding methods like this :

    enum SomeEnum     {          option1("sv")         {             public String toString()             {                 return "Some value";             }              },          option2;          private String PassedValue;          public SomeEnum(String somevalue)         {             this.PassedValue = somevalue;         }          public SomeEnum()         {                 this.PassedValue = "Default Value";         }          public String getPassedValue()         {             return this.PassedValue;         }      } 

is there a way to do something similar in c# or are enums more limited in c#

Answer 1

I wish enums were more powerful in .Net. And I love .Net! You can use attributes to accomplish the same thing. Write the code below once and use it everywhere. This will be a long answer but I think it's a pretty good solution so have patience!

Usage

SomeEnum e = SomeEnum.ValueTwo; string description = e.GetDescription(); 

The Enum

Use attributes to describe the enum and it's values.

[DescriptiveEnumEnforcement(DescriptiveEnumEnforcement.EnforcementTypeEnum.ThrowException)] public enum SomeEnum {     [Description("Value One")]     ValueOne,      [Description("Value Two")]     ValueTwo,      [Description("Value 3")]     ValueThree } 

DescriptionAttribute

/// <summary>Indicates that an enum value has a description.</summary> [AttributeUsage(AttributeTargets.Field)] public class DescriptionAttribute : System.Attribute {     /// <summary>The description for the enum value.</summary>     public string Description { get; set; }      /// <summary>Constructs a new DescriptionAttribute.</summary>     public DescriptionAttribute() { }      /// <summary>Constructs a new DescriptionAttribute.</summary>     /// <param name="description">The initial value of the Description property.</param>     public DescriptionAttribute(string description)     {         this.Description = description;     }      /// <summary>Returns the Description property.</summary>     /// <returns>The Description property.</returns>     public override string ToString()     {         return this.Description;     } } 

DescriptiveEnumEnforcementAttribute

An attribute to ensure your enum's are properly configured.

/// <summary>Indicates whether or not an enum must have a NameAttribute and a DescriptionAttribute.</summary> [AttributeUsage(AttributeTargets.Enum)] public class DescriptiveEnumEnforcementAttribute : System.Attribute {     /// <summary>Defines the different types of enforcement for DescriptiveEnums.</summary>     public enum EnforcementTypeEnum     {         /// <summary>Indicates that the enum must have a NameAttribute and a DescriptionAttribute.</summary>         ThrowException,          /// <summary>Indicates that the enum does not have a NameAttribute and a DescriptionAttribute, the value will be used instead.</summary>         DefaultToValue     }      /// <summary>The enforcement type for this DescriptiveEnumEnforcementAttribute.</summary>     public EnforcementTypeEnum EnforcementType { get; set; }      /// <summary>Constructs a new DescriptiveEnumEnforcementAttribute.</summary>     public DescriptiveEnumEnforcementAttribute()     {         this.EnforcementType = EnforcementTypeEnum.DefaultToValue;     }      /// <summary>Constructs a new DescriptiveEnumEnforcementAttribute.</summary>     /// <param name="enforcementType">The initial value of the EnforcementType property.</param>     public DescriptiveEnumEnforcementAttribute(EnforcementTypeEnum enforcementType)     {         this.EnforcementType = enforcementType;     } } 

Getting the Description

/// <summary>Provides functionality to enhance enumerations.</summary> public static partial class EnumUtil {     /// <summary>Returns the description of the specified enum.</summary>     /// <param name="value">The value of the enum for which to return the description.</param>     /// <returns>A description of the enum, or the enum name if no description exists.</returns>     public static string GetDescription(this Enum value)     {         return GetEnumDescription(value);     }      /// <summary>Returns the description of the specified enum.</summary>     /// <param name="value">The value of the enum for which to return the description.</param>     /// <returns>A description of the enum, or the enum name if no description exists.</returns>     public static string GetDescription<T>(object value)     {         return GetEnumDescription(value);     }      /// <summary>Returns the description of the specified enum.</summary>     /// <param name="value">The value of the enum for which to return the description.</param>     /// <returns>A description of the enum, or the enum name if no description exists.</returns>     public static string GetEnumDescription(object value)     {         if (value == null)         return null;          Type type = value.GetType();          //Make sure the object is an enum.         if (!type.IsEnum)             throw new ApplicationException("Value parameter must be an enum.");          FieldInfo fieldInfo = type.GetField(value.ToString());         object[] descriptionAttributes = fieldInfo.GetCustomAttributes(typeof(DescriptionAttribute), false);          //If no DescriptionAttribute exists for this enum value, check the DescriptiveEnumEnforcementAttribute and decide how to proceed.         if (descriptionAttributes == null || descriptionAttributes.Length == 0)         {             object[] enforcementAttributes = fieldInfo.GetCustomAttributes(typeof(DescriptiveEnumEnforcementAttribute), false);              //If a DescriptiveEnumEnforcementAttribute exists, either throw an exception or return the name of the enum instead.             if (enforcementAttributes != null && enforcementAttributes.Length == 1)             {                 DescriptiveEnumEnforcementAttribute enforcementAttribute = (DescriptiveEnumEnforcementAttribute)enforcementAttributes[0];                  if (enforcementAttribute.EnforcementType == DescriptiveEnumEnforcementAttribute.EnforcementTypeEnum.ThrowException)                     throw new ApplicationException("No Description attributes exist in enforced enum of type '" + type.Name + "', value '" + value.ToString() + "'.");                  return GetEnumName(value);             }             else //Just return the name of the enum.                 return GetEnumName(value);         }         else if (descriptionAttributes.Length > 1)             throw new ApplicationException("Too many Description attributes exist in enum of type '" + type.Name + "', value '" + value.ToString() + "'.");          //Return the value of the DescriptionAttribute.         return descriptionAttributes[0].ToString();     } }