Extension interface patterns

Question

The new extensions in .Net 3.5 allow functionality to be split out from interfaces.

For instance in .Net 2.0

public interface IHaveChildren {
    str         


        

Answer 1

Rob Connery (Subsonic and MVC Storefront) implemented an IRepository-like pattern in his Storefront application. It's not quite the pattern above, but it does share some similarities.

The data layer returns IQueryable which permits the consuming layer to apply filtering and sorting expression on top of that. The bonus is being able to specify a single GetProducts method, for example, and then decide appropriately in the consuming layer how you want that sorting, filtering or even just a particular range of results.

Not a traditional approach, but very cool and definitely a case of DRY.