https://gist.github.com/1313735 https://gist.github.com/1313735 Here's a full example in some production code. I ended up doing it this way to simplify some cr

https://gist.github.com/1313735 https://gist.github.com/1313735 Here's a full example in some production code. I ended up doing it this way to simplify some crazy legacy code. There were a bunch of different classes that provide order items and extended prices in different ways. With this setup as long as those types implement the necessary interfaces, they get those extension methods for free.