Is there some lore about this I don’t know?
There is no C++ allowed in the Linux kernel and Linus has gone on several major rants about how terrible a language it is.
There’s assembly and makefiles too
Less of a joke answer, there has been work to allow Rust bindings for drivers.
According to the github analysis, the kernel repository is:
- C 98.3%
- Assembly 0.7%
- Shell 0.4%
- Makefile 0.2%
- Python 0.2%
- Perl 0.1%
- Other 0.1%
So yeah, its basically all C, plus a tiny bit of assembly for very low level bootstrapping and some helper scripts.
Lots of core UNIX and Linux projects are. C++ is not liked by a lot of low level FOSS community. I think Rust is going to get further into these areas. I know C++ well but prefer C. I know plenty of others who feel the same.
Then why does he write C++?
https://github.com/subsurface/subsurface/commit/1b16d570a1b6700295153bd6597b148b65000458
Torvalds just really dislikes C++. He’s gone on the record saying that he thinks it’s just not a good language. In his own words “C++ is just a waste, there is no design at all, just adding some scum on top of C.”
In the specific use case of kernel programming, maybe. But the Standard Template Library is awesome.
I would have agreed with that before C++11. But since then, C++ has improved a lot. Its like the vision of what C++ suddenly became more clear. So I wonder if Linus would still say that today. (Unfortunately, there have been a lot of missteps in the development of C++ though, and so there is a lot of cruft that everyone wishes was not there…)
”C++ is a horrible language. It’s made more horrible by the fact that a lot of substandard programmers use it, to the point where it’s much much easier to generate total and utter crap with it. Quite frankly, even if the choice of C were to do nothing but keep the C++ programmers out, that in itself would be a huge reason to use C.”
I don’t know about Linus, but the last time Reiser’s wife was seen, she was writing a c++ hello world
For an example from the other poster’s explanation:
https://lwn.net/Articles/249460/
This was pre c++11 - not sure if he’s changed his mind at all with more modern c++
That’s my guess, but there was a conversation on the mailing list a few months ago that wasn’t just immediately shut down, even by other prolific developers
Ts’o seems skeptical, but is at least asking whether c++ has improved
https://lore.kernel.org/lkml/20240110175755.GC1006537@mit.edu/
I don’t think its the ergonomics of the language he has an issue with. If anything C++1x probably just made the original critiques of bloat worse.
In that post, his critiques were around the problems with the STL and everyone using Boost. The STL has improved significantly since then, and it would be a limited subset of c++ if it was ever allowed
There have been mailing list conversations earlier this year, citing that clang/gcc now allowing c++ in their own code might mean they’ve taken care of the issues that made it unusable for kernel code
https://lore.kernel.org/lkml/e5949a27-999d-4b6e-8c49-3dbed32a00bc@zytor.com/
I’m not saying it will happen, but it’s not being shot down as an absolute insanity anymore, and I wouldn’t have expected Rust to be allowed in the kernel, either
”C++ is a horrible language. It’s made more horrible by the fact that a lot of substandard programmers use it, to the point where it’s much much easier to generate total and utter crap with it. Quite frankly, even if the choice of C were to do nothing but keep the C++ programmers out, that in itself would be a huge reason to use C.”
Literally apply that train of thought to JavaScript and JavaScript is in an even worse position than C++
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
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 Runnable these days. Before, if you wanted to run a thread, you needed a separate object that inherited Thread. 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.
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++
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.
Look at the kernel code. It’s full of OOP C. There absolutely are objects in the kernel.
I know it is a complete joke. But every time i think of c++ i am reminded of this prank article https://www-users.york.ac.uk/~ss44/joke/cpp.htm
I wonder what would offend Linus more: A version of the Linux Kernel with C++ or one that breaks the userspace…
You know you want a PHP distribution with a JavaScript interface. Don’t lie to yourself.
Mic looks like earring, can’t unsee it…
