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LINQ distinct with IEquatable is not returning distinct result [duplicate]

This question already has answers here:
LINQ's Distinct() on a particular property
(23 answers)
Closed 19 days ago.
class Program
{
static void Main(string[] args)
{
List<Book> books = new List<Book>
{
new Book
{
Name="C# in Depth",
Authors = new List<Author>
{
new Author
{
FirstName = "Jon", LastName="Skeet"
},
new Author
{
FirstName = "Jon", LastName="Skeet"
},
}
},
new Book
{
Name="LINQ in Action",
Authors = new List<Author>
{
new Author
{
FirstName = "Fabrice", LastName="Marguerie"
},
new Author
{
FirstName = "Steve", LastName="Eichert"
},
new Author
{
FirstName = "Jim", LastName="Wooley"
},
}
},
};
var temp = books.SelectMany(book => book.Authors).Distinct();
foreach (var author in temp)
{
Console.WriteLine(author.FirstName + " " + author.LastName);
}
Console.Read();
}
}
public class Book
{
public string Name { get; set; }
public List<Author> Authors { get; set; }
}
public class Author
{
public string FirstName { get; set; }
public string LastName { get; set; }
public override bool Equals(object obj)
{
return true;
//if (obj.GetType() != typeof(Author)) return false;
//else return ((Author)obj).FirstName == this.FirstName && ((Author)obj).FirstName == this.LastName;
}
}
This is based on an example in "LINQ in Action". Listing 4.16.
This prints Jon Skeet twice. Why? I have even tried overriding Equals method in Author class. Still Distinct does not seem to work. What am I missing?
Edit:
I have added == and != operator overload too. Still no help.
public static bool operator ==(Author a, Author b)
{
return true;
}
public static bool operator !=(Author a, Author b)
{
return false;
}

LINQ Distinct is not that smart when it comes to custom objects.
All it does is look at your list and see that it has two different objects (it doesn't care that they have the same values for the member fields).
One workaround is to implement the IEquatable interface as shown here.
If you modify your Author class like so it should work.
public class Author : IEquatable<Author>
{
public string FirstName { get; set; }
public string LastName { get; set; }
public bool Equals(Author other)
{
if (FirstName == other.FirstName && LastName == other.LastName)
return true;
return false;
}
public override int GetHashCode()
{
int hashFirstName = FirstName == null ? 0 : FirstName.GetHashCode();
int hashLastName = LastName == null ? 0 : LastName.GetHashCode();
return hashFirstName ^ hashLastName;
}
}
Try it as DotNetFiddle

The Distinct() method checks reference equality for reference types. This means it is looking for literally the same object duplicated, not different objects which contain the same values.
There is an overload which takes an IEqualityComparer, so you can specify different logic for determining whether a given object equals another.
If you want Author to normally behave like a normal object (i.e. only reference equality), but for the purposes of Distinct check equality by name values, use an IEqualityComparer. If you always want Author objects to be compared based on the name values, then override GetHashCode and Equals, or implement IEquatable.
The two members on the IEqualityComparer interface are Equals and GetHashCode. Your logic for determining whether two Author objects are equal appears to be if the First and Last name strings are the same.
public class AuthorEquals : IEqualityComparer<Author>
{
public bool Equals(Author left, Author right)
{
if((object)left == null && (object)right == null)
{
return true;
}
if((object)left == null || (object)right == null)
{
return false;
}
return left.FirstName == right.FirstName && left.LastName == right.LastName;
}
public int GetHashCode(Author author)
{
return (author.FirstName + author.LastName).GetHashCode();
}
}

Another solution without implementing IEquatable, Equals and GetHashCode is to use the LINQs GroupBy method and to select the first item from the IGrouping.
var temp = books.SelectMany(book => book.Authors)
.GroupBy (y => y.FirstName + y.LastName )
.Select (y => y.First ());
foreach (var author in temp){
Console.WriteLine(author.FirstName + " " + author.LastName);
}

There is one more way to get distinct values from list of user defined data type:
YourList.GroupBy(i => i.Id).Select(i => i.FirstOrDefault()).ToList();
Surely, it will give distinct set of data

Distinct() performs the default equality comparison on objects in the enumerable. If you have not overridden Equals() and GetHashCode(), then it uses the default implementation on object, which compares references.
The simple solution is to add a correct implementation of Equals() and GetHashCode() to all classes which participate in the object graph you are comparing (ie Book and Author).
The IEqualityComparer interface is a convenience that allows you to implement Equals() and GetHashCode() in a separate class when you don't have access to the internals of the classes you need to compare, or if you are using a different method of comparison.

You've overriden Equals(), but make sure you also override GetHashCode()

The Above answers are wrong!!!
Distinct as stated on MSDN returns the default Equator which as stated The Default property checks whether type T implements the System.IEquatable interface and, if so, returns an EqualityComparer that uses that implementation. Otherwise, it returns an EqualityComparer that uses the overrides of Object.Equals and Object.GetHashCode provided by T
Which means as long as you overide Equals you are fine.
The reason you're code is not working is because you check firstname==lastname.
see https://msdn.microsoft.com/library/bb348436(v=vs.100).aspx and https://msdn.microsoft.com/en-us/library/ms224763(v=vs.100).aspx

You can achieve this several ways:
1. You may to implement the IEquatable interface as shown Enumerable.Distinct Method or you can see #skalb's answer at this post
2. If your object has not unique key, You can use GroupBy method for achive distinct object list, that you must group object's all properties and after select first object.
For example like as below and working for me:
var distinctList= list.GroupBy(x => new {
Name= x.Name,
Phone= x.Phone,
Email= x.Email,
Country= x.Country
}, y=> y)
.Select(x => x.First())
.ToList()
MyObject class is like as below:
public class MyClass{
public string Name{get;set;}
public string Phone{get;set;}
public string Email{get;set;}
public string Country{get;set;}
}
3. If your object's has unique key, you can only use the it in group by.
For example my object's unique key is Id.
var distinctList= list.GroupBy(x =>x.Id)
.Select(x => x.First())
.ToList()

You can use extension method on list which checks uniqueness based on computed Hash.
You can also change extension method to support IEnumerable.
Example:
public class Employee{
public string Name{get;set;}
public int Age{get;set;}
}
List<Employee> employees = new List<Employee>();
employees.Add(new Employee{Name="XYZ", Age=30});
employees.Add(new Employee{Name="XYZ", Age=30});
employees = employees.Unique(); //Gives list which contains unique objects.
Extension Method:
public static class LinqExtension
{
public static List<T> Unique<T>(this List<T> input)
{
HashSet<string> uniqueHashes = new HashSet<string>();
List<T> uniqueItems = new List<T>();
input.ForEach(x =>
{
string hashCode = ComputeHash(x);
if (uniqueHashes.Contains(hashCode))
{
return;
}
uniqueHashes.Add(hashCode);
uniqueItems.Add(x);
});
return uniqueItems;
}
private static string ComputeHash<T>(T entity)
{
System.Security.Cryptography.SHA1CryptoServiceProvider sh = new System.Security.Cryptography.SHA1CryptoServiceProvider();
string input = JsonConvert.SerializeObject(entity);
byte[] originalBytes = ASCIIEncoding.Default.GetBytes(input);
byte[] encodedBytes = sh.ComputeHash(originalBytes);
return BitConverter.ToString(encodedBytes).Replace("-", "");
}

The Equal operator in below code is incorrect.
Old
public bool Equals(Author other)
{
if (FirstName == other.FirstName && LastName == other.LastName)
return true;
return false;
}
NEW
public override bool Equals(Object obj)
{
var other = obj as Author;
if (other is null)
{
return false;
}
if (FirstName == other.FirstName && LastName == other.LastName)
return true;
return false;
}

Instead of
var temp = books.SelectMany(book => book.Authors).Distinct();
Do
var temp = books.SelectMany(book => book.Authors).DistinctBy(f => f.Property);

How to sort a List<T>, by any of its properties?

I'm trying to sort a List<T>, without using OrderBy, OrderByDescending, where T is a custom class.
Code:
class Something
{
public string Category { get; set; }
public int Fingers { get; set; }
public DateTime Creation { get; set; }
}
The list order it's based on any property of T.
class BigRoom
{
var Room = new Room(new List<Something>());
}
class Room<T> where T: class, new()
{
List<T> baseList;
public Room(List<T> listPar)
{
baseList = listPar;
var prop = /* get any property from T with reflection... */
// How to set a comparer here, if we know prop (type, value...)
baseList.Sort(...);
// go do something with reordered list
}
}
I can do it knowing T and its properties, using lambda expressions or delegates.
list.Sort((x, y) => x.CompareTo(y));
But when getting prop values, it returns an object, which it doesn't implement CompareTo(), is there any way of achieving this, if so I'll be grateful.

Your Room constructor can be implemented like this(note i add a random for example purposes you can have the property chosen how you like it):
using System.ComponentModel;
public Room(List<T> listPar)
{
Random r = new Random(Environment.TickCount);
baseList = listPar;
var props = TypeDescriptor.GetProperties(typeof(T));
PropertyDescriptor prop = props[r.Next(props.Count)];
// How to set a comparer here, if we know prop (type, value...)
baseList.Sort((x, y) => prop.GetValue(x).ToString().CompareTo(prop.GetValue(y).ToString()));
// go do something with reordered list
}
So if the propertydescriptor is pointing to the Fingers property for example it will sort by those values,using the compareTo of the string class.

This should get you started. You'll need to actually clean up the Compare method to handle if the values are null i.e. either weren't set or are not IComparable which is required to actually be able to do comparisons.
PropertyInfo myPropertyFromReflection = GetMyPropertySomehow();
myList.Sort(new MyComparer<TransactionRequest>(myPropertyFromReflection));
public class MyComparer<T> : IComparer<T>
{
PropertyInfo _sortBy;
public MyComparer(PropertyInfo sortBy)
{
_sortBy = sortBy;
}
public int Compare(T x, T y)
{
var xValue = _sortBy.GetValue(x) as IComparable;
var yValue = _sortBy.GetValue(y) as IComparable;
return xValue.CompareTo(yValue);
}
}

objectlist is a list of objects you want to sort based on Status, then by Customer Name, then by Company Name, then by Billing Address
Assume entries in the object list have the following properties:
Status,
Customer Name,
Company Name,
Billing Address
objectlist.Sort(delegate(Object a, Object b)
{
if (String.CompareOrdinal(a.Status, b.Status) == 0)
{
return String.CompareOrdinal(a.CustomerName, b.CustomerName) == 0 ? String.CompareOrdinal(a.CompanyName, b.CompanyName) : String.CompareOrdinal(a.BillingAddress, b.BillingAddress);
}
if (a.Status.Equals("Very Important!")) { return -1; }
if (b.Status.Equals("Very Important!")) { return 1; }
if (a.Status.Equals("Important")) { return -1; }
if (b.Status.Equals("Important")) { return 1; }
if (a.Status.Equals("Not Important")){ return -1; }
return 1;
});
Hope this helps. =)

Get distinct list values

i have a C# application in which i'd like to get from a List of Project objects , another List which contains distinct objects.
i tried this
List<Project> model = notre_admin.Get_List_Project_By_Expert(u.Id_user);
if (model != null) model = model.Distinct().ToList();
The list model still contains 4 identical objects Project.
What is the reason of this? How can i fix it?

You need to define "identical" here. I'm guessing you mean "have the same contents", but that is not the default definition for classes: the default definition is "are the same instance".
If you want "identical" to mean "have the same contents", you have two options:
write a custom comparer (IEqualityComparer<Project>) and supply that as a parameter to Distinct
override Equals and GetHashCode on Project
There are also custom methods like DistinctBy that are available lots of places, which is useful if identity can be determined by a single property (Id, typically) - not in the BCL, though. But for example:
if (model != null) model = model.DistinctBy(x => x.Id).ToList();
With, for example:
public static IEnumerable<TItem>
DistinctBy<TItem, TValue>(this IEnumerable<TItem> items,
Func<TItem, TValue> selector)
{
var uniques = new HashSet<TValue>();
foreach(var item in items)
{
if(uniques.Add(selector(item))) yield return item;
}
}

var newList =
(
from x in model
select new {Id_user= x.Id_user}
).Distinct();
or you can write like this
var list1 = model.DistinctBy(x=> x.Id_user);

How do you define identical? You should override Equals in Project with this definition (if you override Equals also override GetHashCode). For example:
public class Project
{
public int ProjectID { get; set; }
public override bool Equals(object obj)
{
var p2 = obj as Project;
if (p2 == null) return false;
return this.ProjectID == m2.ProjectID;
}
public override int GetHashCode()
{
return ProjectID;
}
}
Otherwise you are just checking reference equality.

The object's reference aren't equal. If you want to be able to do that on the entire object itself and not just a property, you have to implement the IEqualityComparer or IEquatable<T>.

Check this example: you need to use either Comparator or override Equals()
class Program
{
static void Main( string[] args )
{
List<Item> items = new List<Item>();
items.Add( new Item( "A" ) );
items.Add( new Item( "A" ) );
items.Add( new Item( "B" ) );
items.Add( new Item( "C" ) );
items = items.Distinct().ToList();
}
}
public class Item
{
string Name { get; set; }
public Item( string name )
{
Name = name;
}
public override bool Equals( object obj )
{
return Name.Equals((obj as Item).Name);
}
public override int GetHashCode()
{
return Name.GetHashCode();
}
}

Here's an answer from basically the same question that will help.
Explanation:
The Distinct() method checks reference equality for reference types. This means it is looking for literally the same object duplicated, not different objects which contain the same values.
Credits to #Rex M.

Isn't simpler to use one of the approaches shown below :) ?
You can just group your domain objects by some key and select FirstOrDefault like below.
More interesting option is to create some Comparer adapter that takes you domain object and creates other object the Comparer can use/work with out of the box. Base on the comparer you can create your custom linq extensions like in sample below. Hope it helps :)
[TestMethod]
public void CustomDistinctTest()
{
// Generate some sample of domain objects
var listOfDomainObjects = Enumerable
.Range(10, 10)
.SelectMany(x =>
Enumerable
.Range(15, 10)
.Select(y => new SomeClass { SomeText = x.ToString(), SomeInt = x + y }))
.ToList();
var uniqueStringsByUsingGroupBy = listOfDomainObjects
.GroupBy(x => x.SomeText)
.Select(x => x.FirstOrDefault())
.ToList();
var uniqueStringsByCustomExtension = listOfDomainObjects.DistinctBy(x => x.SomeText).ToList();
var uniqueIntsByCustomExtension = listOfDomainObjects.DistinctBy(x => x.SomeInt).ToList();
var uniqueStrings = listOfDomainObjects
.Distinct(new EqualityComparerAdapter<SomeClass, string>(x => x.SomeText))
.OrderBy(x=>x.SomeText)
.ToList();
var uniqueInts = listOfDomainObjects
.Distinct(new EqualityComparerAdapter<SomeClass, int>(x => x.SomeInt))
.OrderBy(x => x.SomeInt)
.ToList();
}
Custom comparer adapter:
public class EqualityComparerAdapter<T, V> : EqualityComparer<T>
where V : IEquatable<V>
{
private Func<T, V> _valueAdapter;
public EqualityComparerAdapter(Func<T, V> valueAdapter)
{
_valueAdapter = valueAdapter;
}
public override bool Equals(T x, T y)
{
return _valueAdapter(x).Equals(_valueAdapter(y));
}
public override int GetHashCode(T obj)
{
return _valueAdapter(obj).GetHashCode();
}
}
Custom linq extension (definition of DistinctBy extension method):
// Embedd this class in some specific custom namespace
public static class DistByExt
{
public static IEnumerable<T> DistinctBy<T,V>(this IEnumerable<T> enumerator,Func<T,V> valueAdapter)
where V : IEquatable<V>
{
return enumerator.Distinct(new EqualityComparerAdapter<T, V>(valueAdapter));
}
}
Definition of domain object used in test case:
public class SomeClass
{
public string SomeText { get; set; }
public int SomeInt { get; set; }
}

List<ViewClReceive> passData = (List<ViewClReceive>)TempData["passData_Select_BankName_List"];
passData = passData?.DistinctBy(b=>b.BankNm).ToList();
It will Works ......

Adding new T to empty List<T> using reflection

I'm attempting to set add a new instance of an Officer class to a potentially empty list using reflection.
These are my classes
public class Report(){
public virtual ICollection<Officer> Officer { get; set; }
}
public class Officer(){
public string Name{ get; set; }
}
Simplified code snippet:
Report report = new Report()
PropertyInfo propertyInfo = report.GetType().GetProperty("Officer");
object entity = propertyInfo.GetValue(report, null);
if (entity == null)
{
//Gets the inner type of the list - the Officer class
Type type = propertyInfo.PropertyType.GetGenericArguments()[0];
var listType = typeof(List<>);
var constructedListType = listType.MakeGenericType(type);
entity = Activator.CreateInstance(constructedListType);
}
//The entity is now List<Officer> and is either just created or contains a list of
//Officers
//I want to check how many officers are in the list and if there are none, insert one
//Pseudo code:
if (entity.count = 0)
{
entity.add(new instance of type)
}
Much appreciated!

Use:
object o = Activator.CreateInstance(type); // "type" is the same variable you got a few lines above
((IList)entity).add(o);

You have two options:
1) Using dynamic:
dynamic list = entity;
if (list.Count = 0)
{
list.Add(new instance of type)
}
2) Using Reflection:
var countProp = entity.GetType().GetProperties(BindingFlags.Public | BindingFlags.Instance).First(p => p.Name == "Count");
var count = (int)countProp.GetValue(entity,null);
if(count == 0)
{
var method = entity.GetType().GetMethods(BindingFlags.Instance | BindingFlags.Public).First(m => m.Name == "Add");
method.Invoke(entity,new instance of type);
}

This isn't quite what you asked for but may accomplish the same task.
public static ICollection<T> EnsureListExistsAndHasAtLeastOneItem(ICollection<T> source)
where T : Officer, new()
{
var list = source ?? new List<T>();
if( list.Count == 0 ) list.Add(new T());
return list;
}
If Officer doesn't have a default constructor then you could add a factory callback
public static ICollection<T> EnsureListExistsAndHasAtLeastOneItem
(ICollection<T> source, Func<T> builder)
where T : Officer
{
var list = source ?? new List<T>();
if( list.Count == 0 ) list.Add(builder());
return list;
}

Just type your entity appropriately as a List<Officer> (or an appropriately more abstract type (such as IList)) and use as normal:
entity = Activator.CreateInstance(constructedListType) as IList;
But no need to check whether to insert or not, just insert:
entity.Insert(0, officer);
I'm assuming (based on the fact that you already know how to create instances using reflection) you're not having trouble creating the instance of type Officer.

Edit after re-reading over your question: This doesn't directly answer your question but is rather a suggestion of a different implementation.
You can easily get by without using reflection:
public class TestContainer<T>
{
private readonly List<T> _list;
public TestContainer()
{
_list = new List<T>();
}
public void Add()
{
_list.Add(default(T));
}
}
Then calling e.g.:
var t = new TestContainer<YourClass>();
t.Add();
t.Add();
t.Add();
you will have a list of 3 instances of YourClass by their default value

SortList duplicated key, but it shouldn't

I have a class which implements IList interface. I requires a "sorted view" of this list, but without modifying it (I cannot sort directly the IList class).
These view shall be updated when the original list is modified, keeping items sorted. So, I've introduced a SortList creation method which create a SortList which has a comparer for the specific object contained in the original list.
Here is the snippet of code:
public class MyList<T> : ICollection, IList<T>
{
public SortedList CreateSortView(string property)
{
try
{
Lock();
SortListView sortView;
if (mSortListViews.ContainsKey(property) == false)
{
// Create sorted view
sortView = new SortListView(property, Count);
mSortListViews.Add(property, sortView);
foreach (T item in Items)
sortView.Add(item);
} else
sortView = mSortListViews[property];
sortView.ReferenceCount++;
return (sortView);
}
finally
{
Unlock();
}
}
public void DeleteSortView(string property)
{
try
{
Lock();
// Unreference sorted view
mSortListViews[property].ReferenceCount--;
// Remove sorted view
if (mSortListViews[property].ReferenceCount == 0)
mSortListViews.Remove(property);
}
finally
{
Unlock();
}
}
protected class SortListView : SortedList
{
public SortListView(string property, int capacity)
: base(new GenericPropertyComparer(typeof(T).GetProperty(property, BindingFlags.Instance | BindingFlags.Public)), capacity)
{
}
public int ReferenceCount = 0;
public void Add(T item)
{
Add(item, item);
}
public void Remove(T item)
{
base.Remove(item);
}
class GenericPropertyComparer : IComparer
{
public GenericPropertyComparer(PropertyInfo property)
{
if (property == null)
throw new ArgumentException("property doesn't specify a valid property");
if (property.CanRead == false)
throw new ArgumentException("property specify a write-only property");
if (property.PropertyType.GetInterface("IComparable") == null)
throw new ArgumentException("property type doesn't IComparable");
mSortingProperty = property;
}
public int Compare(object x, object y)
{
IComparable propX = (IComparable)mSortingProperty.GetValue(x, null);
IComparable propY = (IComparable)mSortingProperty.GetValue(y, null);
return (propX.CompareTo(propY));
}
private PropertyInfo mSortingProperty = null;
}
private Dictionary<string, SortListView> mSortListViews = new Dictionary<string, SortListView>();
}
Practically, class users request to create a SortListView specifying the name of property which determine the sorting, and using the reflection each SortListView defined a IComparer which keep sorted the items.
Whenever an item is added or removed from the original list, every created SortListView will be updated with the same operation.
This seems good at first chance, but it creates me problems since it give me the following exception when adding items to the SortList:
System.ArgumentException: Item has already been added. Key in dictionary: 'PowerShell_ISE [C:\Windows\sysWOW64\WindowsPowerShell\v1.0\PowerShell_ISE.exe]' Key being added: 'PowerShell_ISE [C:\Windows\system32\WindowsPowerShell\v1.0\PowerShell_ISE.exe]'
As you can see from the exception message, thrown by SortedListView.Add(object), the string representation of the key (the list item object) is different (note the path of the executable).
Why SortList give me that exception?
To solve this I tried to implement a GetHashCode() for the underlying object, but without success:
public override int GetHashCode()
{
return (
base.GetHashCode() ^
mApplicationName.GetHashCode() ^
mApplicationPath.GetHashCode() ^
mCommandLine.GetHashCode() ^
mWorkingDirectory.GetHashCode()
);
}

If I understood you correctly, your purpose is just to get a view of you list, sorted by a property of the object.
Then, why use SortedList that requires unique Keys, when you could easily get your result using LINQ OrderBy (or if you're using .net 2.0 List.Sort()) ?
Hence, for example, your CreateSortView could be implemented in this way:
(omitting lock, try/finally and reference counting)
public IList<T> CreateSortView(string property)
{
IList<T> sortView;
if (mSortListViews.ContainsKey(property) == false)
{
// Create sorted view
sortView = this.OrderBy(x => x, new GenericPropertyComparer<T>(property)).ToList();
mSortListViews.Add(property, sortView);
}
else
{
sortView = mSortListViews[property];
}
return sortView;
}
With GenericPropertyComparer implemented as follows:
class GenericPropertyComparer<T> : IComparer<T>
{
public GenericPropertyComparer(string propertyName)
{
var property = typeof(T).GetProperty(propertyName, BindingFlags.Instance | BindingFlags.Public);
if (property == null)
throw new ArgumentException("property doesn't specify a valid property");
if (property.CanRead == false)
throw new ArgumentException("property specify a write-only property");
if (property.PropertyType.GetInterface("IComparable") == null)
throw new ArgumentException("property type doesn't IComparable");
mSortingProperty = property;
}
public int Compare(T x, T y)
{
IComparable propX = (IComparable)mSortingProperty.GetValue(x, null);
IComparable propY = (IComparable)mSortingProperty.GetValue(y, null);
return (propX.CompareTo(propY));
}
private PropertyInfo mSortingProperty = null;
}
EDIT:
If you need to add/remove items from your sorted collection frequeltly, maybe use a SortedList would be better, but the problem with SortedList is that it needs unique keys, and in your case you can't assure that.
Anyway, you can use a custom sorted List that doesn't need unique values, look at the link below for a simple implementation:
Implementation of sorted IList<T> that doesn't require unique values

It seems to me it is a multithreading issue. I can't see what the Lock() function is doing in your code, but I think you will have more luck by surrounding the dictionary access code with a standard lock:
lock(this){
SortListView sortView;
if (mSortListViews.ContainsKey(property) == false) {
// Create sorted view
sortView = new SortListView(property, Count);
mSortListViews.Add(property, sortView);
foreach (T item in Items)
sortView.Add(item);
} else
sortView = mSortListViews[property];
sortView.ReferenceCount++;
}
and the same in the removing part.

Thanks to digEmAll's comment, I found a quick solution: The IComparer implementation shall return 0 only on objects really equals!
So:
public int Compare(object x, object y)
{
IComparable propX = (IComparable)mSortingProperty.GetValue(x, null);
IComparable propY = (IComparable)mSortingProperty.GetValue(y, null);
int compare;
if ((compare = propX.CompareTo(propY)) == 0) {
if (x.GetHashCode() < y.GetHashCode())
return (-1);
else if (x.GetHashCode() > y.GetHashCode())
return (+1);
else return (0);
} else
return (compare);
}