Before I go ahead and publish my next article, I have two minor gripes about Extension Method Syntax.  Suppose I have a simple extension method:

public static string FriendlyClassName(this object o)

string className = o.ToString();

return className.Substring(className.LastIndexOf(".") + 1);

I don't care much for explicity use of "this", sice this is basic OO:

//I don't like Extension Methods making me explicitly use "this"

Console.WriteLine(this.FriendlyClassName() + " complete");

I also don't care much for the following being invalid syntax:

Console.WriteLine(base.FriendlyClassName() + " complete");

That one informs me that type "Object" does not contain the FriendlyClassName() method, it would appear that the "this" keyword triggers the syntactical sugar of the extension method paths of the compiler? 

Take a look at the next one, which Dan thinks is wonderful.  Using this extension method:

        public static bool IsNullOrEmpty(this System.Collections.ICollection collection)

        {

            if (null == collection || 0 == collection.Count)

            { return true; }

            return false;           

        }

The following code does not throw any exceptions:

Hmm... you can read about the NullObject pattern here http://www.cs.oberlin.edu/~jwalker/nullObjPattern/

In a disgusting way, we could use a set of Extension Methods to impliment the NullObject pattern.  IF it makes sense in your program, IF doing the usual coding for nulls isn't appropriate, IF the classical Null Object pattern isn't appropirate, IF Nullable<T> isn't appropriate for your scenario.  That's a lot of ifs.  Still, I found this to be useful in certain cases.