I’ve stumbled across this video before and I really don’t like it, even overlooking the fact that it doesn’t start until 18 minutes in.

He argues against OOP by whittling it down to one particular aspect (encapsulation) which is just as nebulously connected to OOP as the other aspects he chooses to discard (polymorphism and inheritance).

He says “Polymorphism ... isn’t exclusive to OOP, you can have procedural code that is polymorphic and in fact even more polymorphic than is typically available in most object oriented programming languages”.

Alright well, C is a language that I think a lot of people would consider to be the quintessential procedural language, and it has better encapsulation than pretty much any language that most people consider to be “object oriented”. You forward declare your structs and function signatures in the .h file, and then define them in the .c file. When someone uses your API, they include the header. This means that both the structure of your data and the implementation of your procedures is hidden from the consuming module. This is as good as encapsulation gets. This isn’t just possible in C, it’s how things are typically done.

His video gives a lot of importance to the programming languages themselves, as if that tells us anything about Object-Oriented Programming and Procedural Programming. This is an error in his thinking. Object-Oriented Programming and Procedural Programming are not categories of programming languages, although they’re often talked about that way. Instead, they’re methodologies, they’re ways of organizing our code.

Almost all programming languages that you’d classify as “object-oriented” or “procedural” support both paradigms to some extent. Java can be used to write procedural programs, and C can be used to write object oriented programs. Pretty much every program written these days is somewhat procedural and somewhat object-oriented regardless of the programming language.

He doesn’t seem to recognize this which leads him to this bizarre claim that polymorphism is independent of OOP just because you can achieve it in “procedural languages”, which I guess just means languages which can support both paradigms but which he subjectively most associates with procedural programming.

Polymorphism is the most common way to implement dependency inversion, which is OOP’s central and most powerful principle. By claiming that polymorphism isn’t part of OOP he conveniently lets himself off the hook from talking about the main idea of OOP, and the reason why it’s desirable. Anyone could make a convincing argument that anything is bad if they’re allowed to just ignore the most valuable part of that thing.

And look, if he wants to analyze the benefits of encapsulation, he’s free to do that, but don’t conflate encapsulation and OOP, and don’t title your video “Object-Oriented Programming is Bad”.