wayne on January 15, 2008 

Great example of sorting a Generic.List<T> collection of objects can be found here.  For future reference for myself, here is a class that can be reused in future projects whenever I need to sort a collection of custom objects:

/// <summary>
/// The generic comparer class allows for sorting on a generic collections property fields
/// </summary>
/// <typeparam name="T">An object</typeparam>
public class GenericComparer<T> : IComparer<T>
{
    /// <summary>
    /// Creates a new instance of the GenericComparer class
    /// </summary>
    /// <param name="sortExpression">A string expression of the field to sort</param>
    /// <param name="sortDirection">A SortDirection value to indicate 
    /// Ascending or Descending sort</param>
    public GenericComparer(string sortExpression, SortDirection sortDirection)
    {
        this.SortExpression = sortExpression;
        this.SortDirection = sortDirection;
    }

    /// <summary>
    /// Private container for the Sort Direction
    /// </summary>
    private SortDirection sortDirection;

    /// <summary>
    /// Private container for the expression used for the sort
    /// </summary>
    private string sortExpression;

    /// <summary>
    /// The expression to use during the sort (in this case, the Generic objects field name)
    /// </summary>
    public string SortExpression
    {
        get { return sortExpression; }
        set { sortExpression = value; }
    }

    /// <summary>
    /// The direction to perform the sort
    /// </summary>
    public SortDirection SortDirection
    {
        get { return this.sortDirection; }
        set { this.sortDirection = value; }
    }

    /// <summary>
    /// Performs the sort on the supplied objects
    /// </summary>
    /// <example>
    /// The following example shows how to implement and use this class:
    /// <![CDATA[
    ///     using System.Collections.Generic;
    ///     public class MyClass {
    ///         public void PerformSort() {
    ///             List<MyGenericObject> items = MyDataObject.GetObjects();
    ///             items.Sort(new GenericComparer<MyGenericObject>(SortExpression, SortDirection));
    ///         }
    ///     }
    /// ]]>
    /// </example>
    /// <param name="x">The first object</param>
    /// <param name="y">The second object</param>
    /// <returns>An int value that specifies the result of the comparison</returns>
    public int Compare(T x, T y)
    {
        PropertyInfo propertyInfo = typeof(T).GetProperty(SortExpression);
        IComparable obj1 = (IComparable)propertyInfo.GetValue(x, null);
        IComparable obj2 = (IComparable)propertyInfo.GetValue(y, null);

        if (SortDirection == SortDirection.Ascending)
            return obj1.CompareTo(obj2);
        else
            return obj2.CompareTo(obj1);
    }
}

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