generics and this keyword in argument list

[puzzlecracker]

In the example below ( it's taken off Jon's blogs), what does this
keyword in the parameter list mean?
Also, why do we need to do specify generic T here WithLogging<T>?
wouldn't type be derived from IEnumerable<T> ?


using System;
using System.Collections.Generic;

public static class Extensions
{
public static IEnumerable<T> WithLogging<T>(this IEnumerable<T>
source,
string name)
{
foreach (T element in source)
{
Console.WriteLine("{0}: {1}", name, element);
yield return element;
}
}
}

 

[Martin Honnen]

In the example below ( it's taken off Jon's blogs), what does this
keyword in the parameter list mean?
Also, why do we need to do specify generic T here WithLogging<T>?
wouldn't type be derived from IEnumerable<T> ?


using System;
using System.Collections.Generic;

public static class Extensions
{
public static IEnumerable<T> WithLogging<T>(this IEnumerable<T>
source,
string name)

It is a static class with a static method using 'this' on the first
argument to define an extension method. So using C# or VB.NET 2008 you
can call a method WithLogging on any IEnumerable<T>.
See http://msdn.microsoft.com/en-us/library/bb383977.aspx for an
introduction to extension methods.

 

[Jon Skeet [C# MVP]]

In the example below ( it's taken off Jon's blogs), what does this
keyword in the parameter list mean?

It's an extension method.

See http://csharpindepth.com/Articles/General/BluffersGuide3.aspx or
http://msdn.microsoft.com/en-us/library/bb383977.aspx