gistfile1.cs

public class ObjectComparer : System.Collections.IComparer
{
  private const int COMPARE_EQUAL = 0;
  private const int COMPARE_GREATERTHAN = 1;
  private const int COMPARE_LESSTHAN = -1;
  private string _propertyNames = string.Empty;
  //params string[] names
  public ObjectComparer(string propertyName){
  this._propertyNames = propertyName;
}

public int Compare(object x, object y){
object a = x.GetType().GetProperty(this._propertyNames).GetValue(x, null);
object b = y.GetType().GetProperty(this._propertyNames).GetValue(y, null);
bool aIsNotNothing = a != null;
bool bIsNotNothing = b != null;
bool notSameType = a.GetType() == b.GetType();
if(aIsNotNothing && !bIsNotNothing){
  return COMPARE_GREATERTHAN;
}
else if(!aIsNotNothing && bIsNotNothing){
  return COMPARE_LESSTHAN;
}
else if(!aIsNotNothing && !bIsNotNothing){
  return COMPARE_EQUAL;
}
else if(notSameType){
  return COMPARE_LESSTHAN;
}

if (a is System.IComparable){
  return (a as System.IComparable).CompareTo(b);
}
else{
  throw new InvalidOperationException(a.GetType().Name + " is not supported by the ObjectComparer.");
}
}
}

gistfile2.cs

public class MultiKeyObjectComparer : System.Collections.IComparer
{
private ObjectComparer[] _comparers;
public MultiKeyObjectComparer(params string[] propertyNames){
this._comparers = this.CreateComparers(propertyNames);
}
private ObjectComparer[] CreateComparers(string[] propertyNames){
System.Collections.ArrayList list = new System.Collections.ArrayList();
foreach(string propertyName in propertyNames){
list.Add(new ObjectComparer(propertyName));
}
return (list.ToArray(typeof(ObjectComparer)) as ObjectComparer[]);
}
public int Compare(object x, object y){
int comparison = 0;
foreach(ObjectComparer comparer in this._comparers){
comparison = comparer.Compare(x, y);
if(comparison != 0)
{
return comparison;
}
}
return comparison;
}
}