Does an Enum exist for Asc or Desc ordering?

Interesting point relating to Windows.Forms.SortOrder and Data.SqlClient.SortOrder

Upon inspection the first has values:

public enum SortOrder
{
    None = 0,
    Ascending = 1,
    Descending = 2,
}

while the second has values:

public enum SortOrder
{
    Unspecified = -1,
    Ascending = 0,
    Descending = 1,
}

Probably a good idea to be consistent, especially if serialising.

• SortOrder in System.Data.SqlClient
• ListSortDirection in System.ComponentModel

SortOrder and ListSortDirection are two valid choices but keep in mind this:

ListSortDirection:

• available in .net verions 1.1 to 4 and silverlight.
• the sort order is mandatory: ListSortDirection has only "Ascending" and "Descending" options so the user has too choose one of them.

SortOrder:

• available only in .net versions 3.5 and 4. No support for silverlight.
• sort order is optional: you also have the "Unspecified" option.

There are more than 8 sorting enums in .NET. It goes to show, even at Microsoft engineers will re-invent the wheel. It's also interesting how wildly the commenting practices and code style varies.

Here are the ones I've found:

1. System.ComponentModel.ListSortDirection

   public enum ListSortDirection {
       /// <devdoc>
       ///    <para>Sort in ascending order.</para>
       /// </devdoc>
       Ascending,
       /// <devdoc>
       ///    <para>Sort in descending order.</para>
       /// </devdoc>
       Descending 
   }
   

2. System.Data.SqlClient.SortOrder

   public enum SortOrder {
       Unspecified     = -1,
       Ascending       = 0,
       Descending      = 1
   }
   

3. System.Data.Linq.SqlClient.SqlOrderType

   internal enum SqlOrderType {
       Ascending,
       Descending
   }
   

4. System.DirectoryServices.SortDirection

   public enum SortDirection
   {
       //
       // Summary:
       //     Sort from smallest to largest. For example, A to Z.
       Ascending,
       //
       // Summary:
       //     Sort from largest to smallest. For example, Z to A.
       Descending
   }
   

5. System.Windows.Forms.SortOrder

   /// <include file='doc\SortOrder.uex' path='docs/doc[@for="SortOrder"]/*' />
   /// <devdoc>
   ///    <para>
   ///       Specifies how items in
   ///       a list are sorted.
   ///    </para>
   /// </devdoc>
   public enum SortOrder {
   
       /// <include file='doc\SortOrder.uex' path='docs/doc[@for="SortOrder.None"]/*' />
       /// <devdoc>
       ///    <para>
       ///       The items are
       ///       not sorted.
       ///    </para>
       /// </devdoc>
       None = 0,
   
       /// <include file='doc\SortOrder.uex' path='docs/doc[@for="SortOrder.Ascending"]/*' />
       /// <devdoc>
       ///    <para>
       ///       The items
       ///       are sorted in ascending order.
       ///    </para>
       /// </devdoc>
       Ascending = 1,
   
       /// <include file='doc\SortOrder.uex' path='docs/doc[@for="SortOrder.Descending"]/*' />
       /// <devdoc>
       ///    <para>
       ///       The items are
       ///       sorted in descending order.
       ///    </para>
       /// </devdoc>
       Descending = 2,
   
   }
   

6. System.Web.Helpers.SortDirection

   public enum SortDirection {
       Ascending,
       Descending
   }
   

7. System.Web.UI.WebControls.SortDirection

   public enum SortDirection {
   
   
       Ascending = 0,
   
   
       Descending = 1
   
   }
   

8. System.Xml.XPath.XmlSortOrder

   public enum XmlSortOrder {
       Ascending       = 1,
       Descending      = 2,
   }
   

9. System.Data.Common.EntitySql.AST.OrderKind

   /// <summary>
   /// Represents order kind (none=asc,asc,desc).
   /// </summary>
   internal enum OrderKind
   {
       None,
       Asc,
       Desc
   }
   

Edit: Another has arrived since this was originally posted.

10. System.Web.UI.DataVisualization.Charting

    /// <summary>
    /// Sorting order (Ascending or Descending).
    /// </summary>
    public enum PointSortOrder
    {
        /// <summary>
        /// Ascending sorting order
        /// </summary>
        Ascending, 
    
        /// <summary>
        /// Descending sorting order
        /// </summary>
        Descending
    }