this post was submitted on 13 Apr 2024
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The day I learned that Linus shares my disdain for all things OOP was such a good day for me.
Me, when Linus' opinion is different to mine: "Linus has such weirdly strong opinions about this"
Me when Linus' opinion is the same as mine: VINDICATION
peak hairless ape
I feel the OOP debate got a bit out of hand. I hate OOP as well, as a paradigm.
But I love objects. An object is just a struct that can perform operations on itself. It's super useful. So many problems lend themselves to the use of objects.
I've been writing a mix of C and C++ for so long I don't even know where the line is supposed to be. It's "C with objects". I probably use only 1% of the functionality of C++, but that 1% is a huge upgrade from bare C IMO.
Agreed. Objects are nice and a great way to program. Composition is great. Traits/interfaces are great. Namespaces are great. Objects are a really nice way to reap the benefits of principles like these.
But then there are aspects of OOP that absolutely suck, like inheritance. I hate inheritance. The rules get very confusing very quickly. For example, try understanding overriding of methods. Do I need to call the superclass method or not? If not, does it get called automatically? If so, in what order? How do these rules change for the constructor? Now repeat this exercise for every OOP language you use and try not to mix them up... Java, C++, Python, etc.
Fortunately, it feels like we rely on inheritance less and less these days. As an example, I really like how Java allows you to implement
Runnablethese days. Before, if you wanted to run a thread, you needed a separate object that inheritedThread. And what if that object needs to inherit from another one too? Things would get out of hand quickly. (This is a very old example, but with lambdas and other new features, things are getting even better now.)Anyway, long story short, I think OOP is a complicated way to achieve good principles, and there are simpler ways to achieve those principles than a full OOP implementation.
I've seen this thing where people dislike inheritance a lot, and I have to admit that I kind of struggle with seeing the issue when it's used appropriately. I write a bunch of models that all share a large amount of core functionality, so of course I write an abstract base class in which a couple methods are overridden by derived models. I think it's beautiful in the way that I can say "This model will do X, Y, Z, as long as there exists an implementation of methods A, B, C, which have these signatures", then I can inherit that base class and implement A, B, and C for a bunch of different cases. In short, I think it's a very useful way to express the purpose of the code, without focusing on the implementation of specific details, and a very natural way of expressing that two classes are closely related models, with the same functionality, as expressed by the base class.
I honestly have a hard time seeing how not using inheritance would make such a code base cleaner, but please tell me, I would love to learn.
What you're describing is an interface. An interface is a contract that ensures you can do something, but doesn't care how.
Abstract classes can have abstract functions. When you do this, you're basically just creating a base class with an interface on top; you're saying "all my children must implement this interface of mine" without having to actually make a separate interface.
Abstract classes also offer additional functionality though, such as the ability to define properties, and default implementations of methods. You can even utilize the base class implementation of the method in your child class, in order to perform extra steps or format your input before you do whatever it is you were doing in the first place.
So, an interface is a contract that allows you to call a method, without having to know the specific class or implementation.
Inheritance is more like "it does everything that X does, but it also does Y and Z." If you're ever finding yourself writing an abstract class with purely abstract methods, you probably want to write an interface instead. That way, you get all the same functionality, but it's more loosely coupled
Epecially when you think in "real" OOP terms:
Abstract classes are "child is a parent", fx "duck is a bird". Bird describes all the traits that all birds have in common. But not all birds fly, so flight must come from an interface. This interface can be passed around to any number of objects, and they're not as tightly coupled because unlike an abstract class, an interface doesnt imply that "duck is a flight". The interface is just something we know the duck can do.
As you can probably tell, I work with OOP on a daily basis and have for years. There are a lot of valid criticisms of the OOP philosophy, and I have heard a lot of good points for the record. I am just educating on the OOP principles because you said you were interested and to clear up any misconceptions.
Well yes, I get the differerence between an interface and a class, and what I write is typically a class, which contains properties and functionality that may or may not be overridden in derived classes.
For example, calling a parent class implementation can be useful when I have a derived model that needs to validate its input in some specific way, but otherwise does the same as the base class.
What I don't understand is why this makes OOP bad?
I think the problem with OOP is something you can see whenever legislation is linked with prestige (it happens a lot in real life). The number of good possible rules is quite limited, and the number of people who want to make a name for themselves by championing them seems to be infinite. If you can't find a good rule to claim as your own, you have to pick a bad rule and try to gaslight people into thinking it's a necessary and beneficial. Enough people do that, and we end up with modern OOP.
He is is OK with OOP. The Linux kernel is full of OPP C, but he doesn't like C++
He writes Qt C++ for his diving app though.
I think Linus did it in C with GTK but who took it moved it C++ and Qt. Lazy searching didn't dig up the story.
It was originally Gtk and they rewrote it with Qt: https://www.youtube.com/watch?v=gGZyVSOnqm0
But Linus does write C++/Qt code: https://github.com/subsurface/subsurface/commit/1b16d570a1b6700295153bd6597b148b65000458
I write C++, but I don't like it. I don't think any one should be claiming Linus doesn't like it because he doesn't know it. If he wants to contribute to this project, it must be C++.
I didn't think anyone was making that claim? Either way I'm certainly not trying to.
Yes, this is true, it's just that he was also included in the decision making process to switch to it in the first place, and I feel like his continued use of it makes me think it doesn't have to be as awful as everyone makes it out to be, or he wouldn't use it at all.
Ask him. It's not like he has publically changed his mind. I think he just went with other developers he had handed the project to.
He’s not though, you should look into it
Look at the kernel code. It's full of OOP C. There absolutely are objects in the kernel.
Yea but all that function pointer indirection can actually hurt performance (especially caching), some things in C++ actually can be faster just because the compiler is better at optimizing for that.
There is nothing you can do in C++ or C, that can't be done in the other. It's the kind of the point of those languages.
Technically you're right, but I don't think that changes what I said about optimization. There are still cases where equivalent C++ code can be faster than the C version merely due to different optimizations used.
Meh, I'm unconvinced. If it's any kind of hot spot, in either, you can optimize the hell out of it. C++ is often more bloated is it's just a harder language pretending to be an easier one.
That's fine, you don't have to agree. Personally I do like to use just a few features of C++ without going too crazy, like simple classes and maybe one level of inheritance, but I don't really get into templates or exceptions or other really complex/controversial stuff. I prefer having the stronger typing and better readability of this kind of C++, and I think it helps me make less mistakes, but I realize not everyone agrees, and that's ok.
I think that's the thing, C++ is so broad. It's like many languages together. It's complex with lots of implicitness yet unsafe. There is loads of support in compilers and tools to mitigate that, but that's treatment not cure.
I think the same could be said about C now too, it is continuing to evolve itself with newer standards too just like C++. People choose to only use C features that they want, same goes for C++.
And that is true of any language, but C++ is without doubt one of the broadest. There are very different ways of working with it that compile very differently.
Is that really such a bad thing though?
Yes. Too much for people to learn, so they make mistakes. I've seen compilers get confused with C++. Though it was MS's....
If a language isn't tight, it should at least be safe. C++ is neither. You can do anything with it, but I don't think it's ever really a good tool for a particular job.
Yeah it's pretty great, especially when so many people are so quick to assume that OOP is essential for managing complexity.
OOP is the poster child for solving the problems that it creates itself.