I was leading our Groovy book club this week and had an insight. We have Java programmers, C/C++ programmers and script writers so we try to use a wide range of examples to illustrate points.
We were discussing closures, which can be challenging for people unfamiliar with them. I was making that point that Closures are Objects which means they are instances of classes. Particularly, they are basically classes with a (generally) single method and no data members.
That made me think about Structs, which are basically classes without methods.
So, I had the thought that Classes = Structs plus Closures.
I'm not sure if this is a helpful insight yet, but anytime I can think of things in a new way I like to explore it a bit. I think the C/C++ programmers in the book club found it helpful, perhaps because they're already used to thinking about different types of objects such as structs. So, thinking about Closures as another kind of class was not such a stretch for them.