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Matt Godbolt sold me on Rust by showing me C++

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Re: Matt Godbolt sold me on Rust by showing me C++

#251

Post by jandrewrogers »

fpoling wrote: post #70
dvratil wrote: post #8

The one thing that sold me on Rust (going from C++) was that there is a single way errors are propagated: the Result type. No need to bother with exceptions, functions returning bool, functions returning 0 on success, functions returning 0 on error, functions returning -1 on error, functions returning negative errno on error, functions taking optional pointer to bool to indicate error (optionally), functions taking r…

Result type still requires quite a few lines of boilerplate if one needs to add custom data to it. And as a replacement of exceptions with automatic stack trace attachment it is relatively poor. In any case I will take Rust Result over C++ mess at any time especially given that we have two C++, one with exception support and one without making code incompatible between two.

FWIW, stack traces are part of C++ now and you can construct custom error types that automagically attach them if desired. Result types largely already exist in recent C++ editions if you want them.

I use completely custom error handling stacks in C++ and they are quite slick these days, thanks to improvements in the language.

Re: Matt Godbolt sold me on Rust by showing me C++

#252

Post by jll29 »

jeroenhd wrote: post #32
dvratil wrote: post #8

The one thing that sold me on Rust (going from C++) was that there is a single way errors are propagated: the Result type. No need to bother with exceptions, functions returning bool, functions returning 0 on success, functions returning 0 on error, functions returning -1 on error, functions returning negative errno on error, functions taking optional pointer to bool to indicate error (optionally), functions taking r…

The result type does make for some great API design, but SerenityOS shows that this same paradigm also works fine in C++. That includes something similar to the ? operator, though it's closer to a raw function call. SerenityOS is the first functional OS (as in "boots on actual hardware and has a GUI") I've seen that dares question the 1970s int main() using modern C++ constructs instead, and the API is simply a lot b…

> I think c++, the language, is ready for the modern world. However, c++, the community, seems to be struck at least 20 years in the past.

Good point. A language that gets updated by adding a lot of features is DIVERGING from a community that has mostly people that still use a lot of the C baggage in C++, and only a few folks that use a lot of template abstraction at the other end of the spectrum.

Since in larger systems, you will want to re-use a lot of code via open source libraries, one is inevitably stuck in not just one past, but several versions of older C++, depending on when the code to be re-used was written, what C++ standard was stable enough then, and whether or not the author adopted what part of it.

Not to speak of paradigm choice to be made (object oriented versus functional versus generic programmic w/ templates).

It's easier to have, like Rust offers it, a single way of doing things properly. (But what I miss in Rust is a single streamlined standard library - organized class library - like Java has had it from early days on, it instead feels like "a pile of crates").

Re: Matt Godbolt sold me on Rust by showing me C++

#253

Post by runevault »

mountainriver wrote: post #223
thrwyexecbrain wrote: post #132

The C++ code I write these days is actually pretty similar to Rust: everything is explicit, lots of strong types, very simple and clear lifetimes (arenas, pools), non-owning handles instead of pointers. The only difference in practice is that the build systems are different and that the Rust compiler is more helpful (both in catching bugs and reporting errors). Neither a huge deal if you have a proper build and testi…

I still find it basically impossible to get started with a C++ project. I tried again recently for a proxy I was writing thinking surely things have evolved at this point. Every single package manager couldn’t handle my very basic and very popular dependencies. I mean I tried every single one. This is completely insane to me. Not to mention just figuring out how to build it after that which was a massive headache and…

When I've dabbled in C++ recently it has felt like using CMake fetching github repos has been the least painful thing I've tried (dabbled in vcpkg and conan a bit), since most libraries are cmake projects.

I am no expert so take it with a grain of salt, but that was how it felt for me.

Re: Matt Godbolt sold me on Rust by showing me C++

#254

Post by oasisaimlessly »

Maxatar wrote: post #234
Etheryte wrote: post #92

Earlier quoted context omitted.

Just like language shapes the way we think and talk about things, programming languages shape both what libraries are written and how. You could write anything in anything so long as it's Turing complete, but in real life we see clearly that certain design decisions at the language level either advantage or disadvantage certain types of solutions. Everyone could in theory write C without any memory issues, but we all…

The Sapir Whorf hypothesis has long been debunked: https://en.m.wikipedia.org/wiki/Linguistic_relativity

The strong hypothesis has been debunked, yes, but nobody is asserting it.

From your link:

> Nevertheless, research has produced positive empirical evidence supporting a weaker version of linguistic relativity:[5][4] that a language's structures influence a speaker's perceptions, without strictly limiting or obstructing them.

Re: Matt Godbolt sold me on Rust by showing me C++

#255

Post by cratermoon »

almostgotcaught wrote: post #250
mountainriver wrote: post #223

Earlier quoted context omitted.

I still find it basically impossible to get started with a C++ project. I tried again recently for a proxy I was writing thinking surely things have evolved at this point. Every single package manager couldn’t handle my very basic and very popular dependencies. I mean I tried every single one. This is completely insane to me. Not to mention just figuring out how to build it after that which was a massive headache and…

> Every single package manager couldn’t handle my very basic and very popular dependencies Well there's your problem - no serious project uses one. > I’m convinced it’s a bunch of masochists People use cpp because it's a mature language with mature tooling and an enormous number of mature libraries. Same exact reason anyone uses any language for serious work.

How can you simultaneously call cpp a mature language with mature tooling and acknowledge that there's no working package manager used by any "serious" project?

Re: Matt Godbolt sold me on Rust by showing me C++

#256

Post by socalgal2 »

I already hated C++ (having written 100s of thousands of lines of it in games and at FAANG)

I'd be curious to know what if any true fixes are coming down the line.

This talk: "To Int or to Uint, This is the Question - Alex Dathskovsky - CppCon 2024" https://www.youtube.com/watch?v=pnaZ0x9Mmm0

Seems to make it clear C++ is just broken. That said, and I wish he'd covered this, he didn't mention if the flags he brings up would warn/fix these issues.

I don't want a C++ where I have to remember 1000 rules and if I get one wrong my code is exploitable. I want a C++ where I just can't break the rules except when I explicitly opt into breaking them.

speaking of which, according to another C++ talk, something like 60% of rust crates are dependent on unsafe rust. The point isn't to diss rust. The point is that a safe C++ with opt into unsafe could be similar to rust's opt into unsafe

Re: Matt Godbolt sold me on Rust by showing me C++

#257

Post by Arnavion »

kllrnohj wrote: post #247
Arnavion wrote: post #121

Earlier quoted context omitted.

>many functions allocate memory and what are they supposed to do when there is no memory left? Return an AllocationError. Rust unfortunately picked the wrong default here for the sake of convenience, along with the default of assuming a global allocator. It's now trying to add in explicit allocators and allocation failure handling (A:Allocator type param) at the cost of splitting the ecosystem (all third-party code,…

> Rust unfortunately picked the wrong default here for the sake of convenience, along with the default of assuming a global allocator. [...] Zig for example does it right by having explicit allocators from the start Rust picked the right default for applications that run in an OS whereas Zig picked the right default for embedded. Both are good for their respective domains, neither is good at both domains. Zig's choic…

Various kind of "desktop" applications like databases and video games use custom non-global allocators - per-thread, per arena, etc - because they have specific memory allocation and usage patterns that a generic allocator does not handle as well as targeted ones can.

My current $dayjob involves a "server" application that needs to run in a strict memory limit. We had to write our own allocator and collections because the default ones' insistence on using GlobalAlloc infallibly doesn't work for us.

Thinking that only "embedded" cares about custom allocators is just naive.

Re: Matt Godbolt sold me on Rust by showing me C++

#258

Post by xarope »

This reminds me of SQL's constraints, or pydantic's custom types and validators, which can validate that a value should be an int, and between 0-999, and not exceed, e.g. -1 or 1000.

pydantic is a library for python, but I'm not aware of anything similar in rust or golang that can do this yet? (i.e. not just schema validation, but value range validation too)

Re: Matt Godbolt sold me on Rust by showing me C++

#259

Post by dzaima »

titzer wrote: post #18
writebetterc wrote: post #4

Yes, Rust is better. Implicit numeric conversion is terrible. However, don't use atoi if you're writing C++ :-). The STL has conversion functions that will throw, so separate problem.

> Implicit numeric conversion is terrible. It's bad if it alters values (e.g. rounding). Promotion from one number representation to another (as long as it preserves values) isn't bad. This is trickier than it might seem, but Virgil has a good take on this ( https://github.com/titzer/virgil/blob/master/doc/tutorial/Nu... ). Essentially, it only implicitly promotes values in ways that don't lose numeric information an…

Even that is somewhat bad, e.g. it means you miss "some_u64 = some_u32 * 8" losing bits due to promoting after the arith op, not before.

Re: Matt Godbolt sold me on Rust by showing me C++

#260

Post by morsecodist »

mountainriver wrote: post #223
thrwyexecbrain wrote: post #132

The C++ code I write these days is actually pretty similar to Rust: everything is explicit, lots of strong types, very simple and clear lifetimes (arenas, pools), non-owning handles instead of pointers. The only difference in practice is that the build systems are different and that the Rust compiler is more helpful (both in catching bugs and reporting errors). Neither a huge deal if you have a proper build and testi…

I still find it basically impossible to get started with a C++ project. I tried again recently for a proxy I was writing thinking surely things have evolved at this point. Every single package manager couldn’t handle my very basic and very popular dependencies. I mean I tried every single one. This is completely insane to me. Not to mention just figuring out how to build it after that which was a massive headache and…

Agreed. I have had almost the same experience. The package management and building alone makes Rust worth it for me.
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