The good news is Linux now adopt Rust. In the end it will be all Rust although it may take a long time to migrate from C.
This is a very condescending statement. In fact, for most software, when given the option of a full rewrite from C/C++ to another language, Rust is usually the least reasonable option. Fully automatic memory-managed languages should be considered first.
> People who actually use Rust known it is worth to rewrite C/C++ software in Rust, either the whole or part by part.
A full rewrite is not a feasible option for many large projects, and Rust does not make it easy to rewrite C++ code piece by piece, as the linked article clearly explains.
It's not true that developers don't like full rewrites. Most often, it's the path most developers would choose if they had enough time and funding. But in reality, you don't get either of those two.
And even if you are willing to do a full rewrite, your project probably has non-trivial dependencies on large, mature C++ libraries. You are not going to rewrite those. This is why more new projects are started in C++ every day than in Rust.
I doubt it. You can use C libraries from Rust, and emit C libraries in C++.
> because they themselves don't want to learn a new thing or because they don't want their employees spending time learning a new thing.
Whining about others not wanting to learn when you could have learned how Rust FFI works is, really, hilarious :-)
If the software was originally written in C/C++ based on some performance reasons (avoiding GC/being in control of boxing/being in control of when to use vtables etc.) then what would be more reasonable options?
> Fully automatic memory-managed languages should be considered first.
Those languages have existed for 20+ years so if they were ruled out as part of the original decision making then they probably still aren't applicable.
Plenty of software has been written in C or C++, only because they were the only compiled languages known to the authors.
Having said this, Go, D, Swift, OCaml, Haskell, Common Lisp, C#, F#, Java (with GraalVM, OpenJ9).
All of them offer ways to do AOT compilation and use value types, granted Java is too verbose using Panama for that, and one is better of choosing one of the others.
Some examples, one per language, there are others I could list.
https://www.wildernesslabs.co/
https://www.ptc.com/en/products/developer-tools/perc
https://www.swift.org/get-started/embedded/
https://wiki.dlang.org/Programming_in_D_tutorial_on_Embedded...
There are huge C++ code bases that are 15+ years old and are still actively maintained because the cost of a rewrite is too high for something that still solves the problem well enough.
Most of the large C++ projects I've worked on were written in C++ because it was the most common and mainstream language given the CPU and memory constraints of that time. We have significantly more powerful CPUs now, especially considering multicore computing, and easily 5-10x more RAM than 15 years ago. Java/Kotlin, C#, Go, TypeScript, Swift etc., are perfectly applicable to many more problem domains where C++ once dominated. I can easily agree that many C++ projects would be better off transitioning to a fully garbage-collected language than to Rust.
They were ruled out when the RAM/CPU budget per $SERVER could have been an expensive 4GB/2-core for a complex server processing transactions in real-time.
Today, that same complex server can cheaply run on a 48GB/6-cpu server. Those performance constraints for exactly the same $FUNCTIONALITY are such a low hurdle, dollar-wise, that it makes no sense in most applications of this heuristic.
Of which none has solved concurrency. Some like Java prevents UB but garbage data will still be produced if you don’t diligently protect the access of the shared data.
The hope when Java developed this memory model was that loss of SC is something humans can cope with, it was not, the behaviour is too strange.
To solve interweaving, add mutexes. And once you have mutexes you'll be protected from weak memory models.
Well, the result is safe but unknowable. I would call that garbage data.
Why? If it was written in C++, there's a good chance it was so for performance reasons. You wouldn't want to throw that away with a GC.
I agree. But imagine that games like Doom or Quake would have been unthinkable if they weren't fully written in C/C++. Now, however, we have 3D game engines like Unity that expose a C# API for game logic scripting, and it seems to work just fine. Performance is becoming less of a concern for more and more problem domains.
It is like saying C libraries are Python, only because they happen to be used from Python bindings.
Both of us are old enough to remember when any useful compiled language used to allow for inline Assembly, extension or not.
My view at this point is that you are better off starting from a clean sheet of paper in Rust than trying to make Rust do C++ things it was not designed to do.
In the specific narrow case of performance-engineered code, Rust also seems to consistently produce slower code in my experience for myriad weird reasons, it isn’t one thing. In many cases I don’t even think it is the fault of the language per se, just a side effect of other factors. Nonetheless, customers don’t care about any of that, they won’t accept a performance regression just because you rewrote it.
s/m/b/ too
Non-trivial C++ programs depend on OOP design patterns, webs of shared-mutable objects, and other features which Rust doesn't want to support (Rust's safety also comes from not having certain features that defeat static analysis).
Rust really needs things written the Rust way. It's usually easier with C, because it won't have clever templates and deep inheritance hierarchies.
Even if your goal is to move to Rust, it may make sense to start with Carbon or Circle to refactor the code first to have more immutability and tree-like data flow.
Do you by chance work at Cloudflare, who has migrated away from Lua to Rust?
Curious to hear observations on productivity hit going from Lua to Rust.
Rust modules can handle any traffic themselves, instead of a split between native code and Lua that is too slow to do more than config (Lua is relatively fast for a scripting language, but on the critical path it was a "peanut butter" slowdown adding latency).
At the size and complexity of a server serving 20% of the Web, Lua's dynamic typing was scary. Modules in Rust can enforce many more requirements.
Rust's solid dependency management also helps share implementations and config logic across modules and even different products, instead of everything having to go literally through the same server.
In case you’re not aware, Cloudflare ran on LuaJIT (not just for config) until not that long ago.
Technically correct by ISO C++, in practice that isn't the way to write modern code.
The expectation is that over the next say, decade, Rust gets more trusted by Linux maintainers and perhaps grows more platform support e.g. via the GNU Compiler Collection, and simultaneously some of the dustier platforms "rust out" of Linux because the few maintainers stop caring about new Linux versions. So one day you can rewrite core subsystems in Rust if that makes sense.