alt Hacker Newsa) I'm not sure what OOP is, and it doesn't seem like the people who tout it are either. I'm sure someone would look at code I think is good and call it OOP, and someone who wouldn't. It is so many buzzwords old at this point that using it is more a label of a viewpoint than a coding style. Combined with the book's apparent focus on TDD and carefully selecting names, it zeros me precisely in on a set of people I have worked with over the years. I don't, as a rule, like the code those people generate.
b) The best style is no style, or at least pick a more recently popular dogma like FP, at least it gets you easy/safe parallelism in exchange for throwing some of the tools out of your toolbox.
The core of OOP is encapsulation (into objects) and polymorphic interfaces. You program against interfaces with well-defined contracts. Implementation details are encapsulated behind those interfaces. The same interface can have different implementations. The same interface-typed variable can point to different implementations at different times within the same program execution. The caller who invokes operations on an interface is supposed to not care about the implementation details behind it, and thus be decoupled from them. Interfaces can have an inheritance/subtyping relationship. (Implementations may as well, but that’s optional.) This enables abstracting over the commonalities of several related interfaces without having to introduce an adapter/proxy object. That’s basically it.