What is the best or most interesting use of Extension Methods you've seen? [closed]

Answer 1

Well this isn't exactly clever but I've modified the ----OrDefault methods so you could specify a default item inline instead of checking for null later in your code:

    public static T SingleOrDefault ( this IEnumerable source, 
                                    Func action, T theDefault )
    {
        T item = source.SingleOrDefault(action);

        if (item != null)
            return item;

        return theDefault;
    }

Its incredible simple but really helps clean up those null checks. Best used when your UI is expecting a list of X items, like a tournament system, or game player slots and you want to display "empty seats".

Usage:

    return jediList.SingleOrDefault( 
                 j => j.LightsaberColor == "Orange", 
               new Jedi() { LightsaberColor = "Orange", Name = "DarthNobody");