How to explain an object?

Question

It\'s been years since I thought of this, but I am training some real juniors soon and need to explain what an object is to someone who doesn\'t know what it is.

B

Answer 1

The animal/car metaphors exist to explain the philosophy of object oriented design, which is far more important to understand than just the implementation.

If you skip the metaphors and start with just "it's just variables and functions to deal with them", you're missing any description of responsibility. I constantly deal with developers who give no consideration to class responsibility (see CRC Cards), but instead put data and methods into classes wherever they happen to be editing at the time.

You also miss out on "tell, don't ask". The animal metaphor works well here. In OO, I tell the dog to clean himself. I don't ask him how he's going to do it, because that's a black box I don't want to see inside. The dog knows so I don't need to.

Just be sure to teach your students that these are just metaphors, not the actual thing. A "perfect storm" in the "mortgage meltdown" does not actually involve either storms or anything melting.