[ryao]

The article mentions file_operations, but ignores that it has what would be a static member function in C++ in the form of ->check_flags(), which is never in a vtable. The article author is describing overlap between object oriented programming and something else, called data abstraction, which is what is really being done inside Linux, and calling it OOP.

You can implement OOP in C if you do vtables for inheritance hierarchies manually, among other things, but that is different than what Linux does.

[1718627440]

I honestly don't think how a C++ compiler chooses to implement an object method does matter here.

It's a function belonging to an object, to which is dynamically dispatched with something I would call a vtable. To me that sounds like a classic example of OOP.

Data abstraction is a core of OOP.

This pattern can be used to implement inheritance, when it isn't here that doesn't mean its not OOP.

[ryao]

Data abstraction is a separate invention from OOP since it involves abstract data types. What is being used here is an abstract data type. It is not the pattern used in OOP languages and it is not OOP. It bears similarities and overlap with the vtables used to implement some OOP languages. It is like how thumbs bear similarities and overlap with index fingers, but the two are not the same.

[1718627440]

To cite Wikipedia:

> Object-oriented programming (OOP) is a programming paradigm based on the object – a software entity that encapsulates data and function(s). An OOP computer program consists of objects that interact with one another. A programming language that provides OOP features is classified as an OOP language [...]

You don't disagree, that this kernel pattern is about data abstraction. You probably don't disagree, that the kernel uses functions. The kernel uses "objects" (FS implementations) that follow a defined set of functions, sometimes called "class" (vtables/wtables/however you like to call them). Therefore I conclude what the kernel does here is a prime example of OOP.

[ryao]

You can use similar logic to declare English to be an example of Chinese. They both have syllables. They both assemble syllables into words that convey meaning. They both use grammars to form relationships between those words. Thus, they must be the same. It is fallacious logic. Some similarities do not make things the same. Data abstraction is also its own topic that is able to stand independently from OOP. What the kernel does is data abstraction, not OOP. What you are seeing in the kernel are the abstract data types of data abstraction.

[1718627440]

Sorry no, thus are very different, but of course that's not what you arguing for.

I know ADT and OOP are different concepts, in another answer I wrote what I think the base differences are. But they are related, and in the definitions I am familiar with, ADTs are a base concept for OOP. And OOP can be an implementation for ADTs.

If you don't think the implementations I provide are enough to apply to the kernel, can maybe provide your own definition according to which we can evaluate this, because I feel like we are beating around the bush. But please not something that says this can only be happening in an OOP language, to these I would plainly disagree with, because OOP is a paradigm and not a property of a language.