When approaching an extensibility model, I often find cases in which I want to merely tweak the existing behavior of the default implementation and wish I didn’t have to create a whole new specific type to do so. Instead of creating a specific type, I tend to write a decorator class that implements the interface and takes in both the default instance of that interface and a delegate (specified using a lambda of course). Let’s look at a quick example to make all this abstract talk more concrete. I’m playing around with the NVelocity View Engine...