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I'm not sure Rust is in the same space as C++, so I'm not sure I'd call it a better C++.

I use C++ because I want performance without all the accounting operations that have to happen in C. I try to write my code in a safe way, but language safety just isn't a priority for me. I guess that's why I'm not using Rust. Fighting the borrow checker doesn't seem worth it to me to gain something that's just not that much of a priority. But I'm not writing an OS or a server.

I'd think of Rust more like a better Ada or some language where safety is first priority




Story time: Chrome is a Frankenstein of C and C++ code (both directly and through called libraries, static or dynamic). Now C++ has `std::string` obviously. C of course has `const char *`. To facilitate interoperability C++ has various methods to implicitly or explicitly convert between the two.

At one point it was found these every keypress on the OmniBar resulted in 25,000 string copies.

So my point is that you can write C++ as carefully as you can but on any sufficiently complex code base you'll going to need a pointer to something and then you've really lost all control and safety so the safety in C++ is a bit of an illusion.



Well, that's horrifying. Presumably the value is being copied whenever it is converted from a const char * to a std::string?

The right thing (TM) would probably be to refactor some of the std::string's into std::string_view's, for instance by adding overloads where it makes sense. I doubt you could avoid all the copies, but I think you could cut it down substantially if you collected metrics and focused on the most egregious cases.

Of course, I do not envy the person who is tasked with doing that, and I could be wrong for any number of arcane technical reasons.


I can only imagine that using std::string_view in a massive, complex application would be horrifying.

The borrow checker is one of the benefits of Rust in that case, simply because you can avoid copies while actually being able to trust that you're not opening the door to security & maintenance hell in the process.


Fun fact: this happened during the standardization of std::string_view, which ended up landing in C++17, a few years after this was fixed. Not that there weren't non-standard versions that existed.

In the end they did a number of things to fix this, the patches are linked in the story I linked above.

std::string_view has seemed, to this relative outsider, to be semi-controversial. It makes it pretty easy to introduce use after frees, that it's not null terminated can be easy to forget, and isn't bounds checked. So while it helps with some issues, it can create others, meaning it's not always a clear win.


a lot of the copies might be bits of code defensively copying the string because they don't want to deal with working out lifetime safety.


Fair but I never said it was safe, just that perfect safety isnt of interest to me


I don't really see the distinction you're making. C++ will still be around for legacy projects that don't want to switch, but I can't think of a new project that would benefit from picking C++ over Rust, apart from needing to integrate with the C++ ecosystem beyond what bindgen offers.

You get to write code that's just as or more performant, and you get to jettison the decades of bad language design that is C++, which is win/win to me.


The pool of C++ engineers is much bigger, and like it or not its a very proven solution. Rust still seems to have a lot of areas where its immature (gui toolkits for example)


Maybe because Rust is not a language made to make GUI applications? For GUI applications you are better of with a higher level language.


Don't you think that's a weird limitation though? Nobody says C++ isn't a language made to make GUI applications. If you're going to replace C++ you should probably be able to do the same things at least as well.


It's not actually a limitation, the ecosystem is just young:

https://github.com/iced-rs/iced

My general point though is that there's still some ecosystem/legacy reasons to stick with C++, but Rust very much fills the same niches as C++.


It's not "language safety", it's memory safety. You're saying that memory safety isn't a priority?

When you run Coverity or other static analyzer on your code, how many violations do you find? How many were unexpected?

The borrow checker is always being run - the difference is whether its in the compiler (Rust) or you in your head (C++). And I trust the compiler much more than I trust myself...


For what I use C++ for (game development and embedded systems), smart pointers are "good enough". Especially single player games, worst you run into is a crash, or my arduino code writes past a buffer.




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