I implemented an extension "MyExtensionSortMethod" to sort collections (IEnumerate). This allows me to replace code such as 'entities.OrderBy( ... ).ThenByDescending( ...)' by 'entities.MyExtensionSortMethod()' (no parameter as well).
Here is a sample of implementation:
//test function
function Test(IEnumerable<ClassA> entitiesA,IEnumerable<ClassB> entitiesB ) {
//Sort entitiesA , based on ClassA MySort method
var aSorted = entitiesA.MyExtensionSortMethod();
//Sort entitiesB , based on ClassB MySort method
var bSorted = entitiesB.MyExtensionSortMethod();
}
//Class A definition
public classA: IMySort<classA> {
....
public IEnumerable<classA> MySort(IEnumerable<classA> entities)
{
return entities.OrderBy( ... ).ThenBy( ...);
}
}
public classB: IMySort<classB> {
....
public IEnumerable<classB> MySort(IEnumerable<classB> entities)
{
return entities.OrderByDescending( ... ).ThenBy( ...).ThenBy( ... );
}
}
//extension method
public static IEnumerable<T> MyExtensionSortMethod<T>(this IEnumerable<T> e) where T : IMySort<T>, new()
{
//the extension should call MySort of T
Type t = typeof(T);
var methodInfo = t.GetMethod("MySort");
//invoke MySort
var result = methodInfo.Invoke(new T(), new object[] {e});
//Return
return (IEnumerable < T >)result;
}
public interface IMySort<TEntity> where TEntity : class
{
IEnumerable<TEntity> MySort(IEnumerable<TEntity> entities);
}
However, it seems a bit complicated compared to what it does so I was wondering if they were another way of doing it?
Why don't you use a Predicate for this? It would allow you to pass your sorting conditions as a delegate .
The example below doesn't sort, but it should serve as a decent example of the technique:
private class Book
{
public string Author { get; set; }
public string Name { get; set; }
public DateTime Published { get; set; }
}
//Create and fill a list of books
private List<Book> Books = new List<Book> {
new Book { Author="Mcconnell",Name="Code Complete", Published=new DateTime(1993,05,14) },
new Book { Author="Sussman",Name="SICP (2nd)", Published=new DateTime(1996,06,01) },
new Book { Author="Hunt",Name="Pragmatic Programmer", Published=new DateTime(1999,10,30) },
};
// returns a new collection of books containing just SICP and Pragmatic Programmer.
private IEnumerable<Book> BooksPublishedAfter1995()
{
return Books.FindAll(Book => Book.Published > new DateTime(1995, 12, 31));
}
http://www.rvenables.com/tag/predicates/
Then again, now we're back to OrderBy, aren't we?
If you want to specify a custom sort for your objects, you can implement the IComparable interface on your class. See the following article that explains how to do it:
Implementing IComparable for Sorting Custom Objects
http://codebetter.com/blogs/david.hayden/archive/2005/02/27/56099.aspx
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