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The C++ standard for the F-35 Fighter Jet [video]

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Re: The C++ standard for the F-35 Fighter Jet [video]

#301

Post by zeroc8 »

skepti wrote: post #277
IshKebab wrote: post #272

Earlier quoted context omitted.

I agree. First of all I don't think Ada is a difficult language to learn. Hire C++ programmers and let them learn Ada. Secondly, when companies say "we can't hire enough X" what they really mean is "X are too expensive". They probably have some strict salary bands and nobody had the power to change them. In other words there are plenty of expensive good Ada and C++ programmers, but there are only cheap crap C++ progr…

As I wrote to someone else: Why require that companies use a specific programming language instead of requiring that the end product is good? > And the F35 and America's combat readiness would be in a better place today with Ada instead of C++. What is the evidence for this? Companies selling Ada products would almost certainly agree, since they have a horse in the race. Ada does not automatically lead to better, mor…

Ada and especially Spark makes it a whole lot easier to produce correct software. That doesn't mean it automatically leads to better software. The programming language is just a small piece of the puzzle. But an important one.

Re: The C++ standard for the F-35 Fighter Jet [video]

#302

Post by quietbritishjim »

anonymousiam wrote: post #81

The same is true for the software that runs many satellites. Use of the STL is prohibited. The main issue is mission assurance. Using the stack or the heap means your variables aren't always at the same memory address. This can be bad if a particular memory cell has failed. If every variable has a fixed address, and one of those addresses goes bad, a patch can be loaded to move that address and the mission can contin…

> Using the stack or the heap means your variables aren't always at the same memory address.

Your mention of STL makes it sound like you're talking about C++. But I don't know of any C++ compiler that lets you completely avoid use of the stack, even if you disable the usual suspects (RTTI and exceptions). Sure, you'd have to avoid local variables, defined within a function's body (or at block scope), but that's nowhere near enough.

* The compiler would need to statically allocate space for every function's parameters and return address. That's actually how early compilers did work, but today it would be inefficient because there are surely so many functions defined in a program's binary compared to the number being executed at any given time. (Edit: I suppose you already need the actual code for those functions, so maybe allocating room for their parameters is not so bad.)

* It would also mean that recursion would not work, even mutual recursion (so you'd need runtime checks because this would be hard to detect at compile/link time), although I suspect this is less of a problem than it sounds, but I'm not aware of a C++ compiler that supports it.

* You'd also need to avoid creating any temporary variables at all e.g. y = a + b + c would not be allowed if a,b,c are non-trivial types. (y = a + b would be OK because the temporary could be constructed directly into y's footprint, or stored temporarily in the return space of the relevant operator+(), which again would be statically allocated).

Is that really what you meant? I suspect not, but without all that your point about avoiding the stack doesn't make any sense.

Re: The C++ standard for the F-35 Fighter Jet [video]

#303

Post by bluGill »

jandrewrogers wrote: post #89
dzonga wrote: post #83

I guess a bigger conversation could be had in regards to: what leads to better code in terms of understandability & preventing errors Exceptions (what almost every language does) or Error codes (like Golang) are there folks here that choose to use error codes and forgo Exceptions completely ?

There isn't much of a conversation to be had here. For low-level systems code, exceptions introduce a bunch of issues and ugly edge cases. Error codes are cleaner, faster, and easier to reason about in this context. Pretty much all systems languages use error codes. In C++, which supports both, exceptions are commonly disabled at compile-time for systems code. This is pretty idiomatic, I've never worked on a C++ code…

What you wrote is historically correct, but new analisys shows exceptions are faster that error codes if you actually check the error codes. Of course checking error codes is tedious and so often you don't. Also is micro benchmarks error codes are faster and only when you do more complex benchmarks do exceptions show up as faster.

Re: The C++ standard for the F-35 Fighter Jet [video]

#304

Post by lallysingh »

ecshafer wrote: post #231
bri3d wrote: post #109

https://web.archive.org/web/20111219004314/http://journal.th... (referenced, at least tangentially, in the video) is a piece from the engineering lead which does a great job discussing Why C++. The short summary is "they couldn't find enough people to write Ada, and even if they could, they also couldn't find enough Ada middleware and toolchain." I actually think Ada would be an easier sell today than it was back the…

I've always strongly disliked this argument of not enough X programmers. If the DoD enforces the requirement for Ada, Universities, job training centers, and companies will follow. People can learn new languages. And the F35 and America's combat readiness would be in a better place today with Ada instead of C++.

No they won't. DoD is small compared to the rest of the software market. You get better quality and lower cost with COTS than with custom solutions, unless you spend a crap ton. The labor market for software's no different.

Everyone likes to crap on C++ because it's (a) popular and (b) tries to make everyone happy with a ton of different paradigms built-in. But you can program nearly any system with it more scalably than anything else.

Re: The C++ standard for the F-35 Fighter Jet [video]

#305

Post by skepti2 »

bri3d wrote: post #109

https://web.archive.org/web/20111219004314/http://journal.th... (referenced, at least tangentially, in the video) is a piece from the engineering lead which does a great job discussing Why C++. The short summary is "they couldn't find enough people to write Ada, and even if they could, they also couldn't find enough Ada middleware and toolchain." I actually think Ada would be an easier sell today than it was back the…

> It seems to me that the software field overall has become more open to a wider variety of languages and concepts, and knowing Ada wouldn't be perceived as widely as career pidgeonholing today.

Are you sure? I cannot even find Ada in [0].

I tried modifying some Hello World example in Ada some weeks ago, and I cannot say that I liked the syntax. Some features were neat. I had some trouble with figuring out building and organizing files. Like C++, and unlike Rust I think, there are multiple source file types, like how C++ has header files. I also had trouble with some flags, but I was trying to use some experimental features, so I think that part was on me.

[0]: https://redmonk.com/sogrady/2025/06/18/language-rankings-1-2...

Re: The C++ standard for the F-35 Fighter Jet [video]

#306

Post by TuxSH »

repelsteeltje wrote: post #274
cminmin wrote: post #257

Earlier quoted context omitted.

your programs have a data segment. its not the heap nor the stack... and it can be (depending on loader/linker) a source of reliable object->address mappings as its not dynamically populated.

That sounds like your answer is: "Yes, global variables". That may be a perfectly good solution in many embedded environments, but in most other context's global variables are considered bad design or very limiting and impractical.

> global variables are considered bad design

Global mutable variables, and they usually tend to be grouped into singletons (solving initialization issues, and fewer people bat an eye)

Re: The C++ standard for the F-35 Fighter Jet [video]

#307

Post by unloader6118 »

varjag wrote: post #271
j16sdiz wrote: post #243

Earlier quoted context omitted.

It is more than that. This is what make remote debugging possible. It is impossible to do interactive remote debugging over a ultra low bandwidth link. If everything have static address and deterministic static, you can have a exact copy on ground and debug there.

Interactive debugging is apparently possible and was reportedly done on Deep Space One mission. One of developers involved frequents HN I believe.

Kind of. That took hours of not days.

A local exact replica with deterministic state save lots of time.

Re: The C++ standard for the F-35 Fighter Jet [video]

#308

Post by skepti2 »

zeroc8 wrote: post #301
skepti wrote: post #277

Earlier quoted context omitted.

As I wrote to someone else: Why require that companies use a specific programming language instead of requiring that the end product is good? > And the F35 and America's combat readiness would be in a better place today with Ada instead of C++. What is the evidence for this? Companies selling Ada products would almost certainly agree, since they have a horse in the race. Ada does not automatically lead to better, mor…

Ada and especially Spark makes it a whole lot easier to produce correct software. That doesn't mean it automatically leads to better software. The programming language is just a small piece of the puzzle. But an important one.

> Ada and especially Spark makes it a whole lot easier to produce correct software.

Relative to what? There are formal verification tools for other languages. I have heard Ada/SPARK is good, but I do not know the veracity of that. And Ada companies promoting Ada have horses in the race.

And Ada didn't prevent the Ada code in Ariane 5 from being a disaster.

> The programming language is just a small piece of the puzzle. But an important one.

100% true, but the parent of the original post that he agreed with said:

> And the F35 and America's combat readiness would be in a better place today with Ada instead of C++.

What is the proof for that, especially considering events like Ariane 5?

And Ada arguably has technical and non-technical drawbacks relative to many other languages.

When I tried Ada some weeks ago for a tiny example, I found it cumbersome in some ways. Is the syntax worse and more verbose than even C++? Maybe that is just a learning thing, though. Even with a mandate, Ada did not catch on.

Re: The C++ standard for the F-35 Fighter Jet [video]

#309

Post by zeroc8 »

billforsternz wrote: post #196
msla wrote: post #58

Earlier quoted context omitted.

At that point, why not write in C? Do they think it's C/C++ and not understand the difference? > no recursion Does this actually mean no recursion or does it just mean to limit stack use? Because processing a tree, for example, is recursive even if you use an array, for example, instead of the stack to keep track of your progress. The real trick is limiting memory consumption, which requires limiting input size.

Semi serious idea: A lot of people (including me) write C++ but it's basically C plus a small set of really ergonomic and useful C++ features (eg references). This should be standardised as a new language called C+

That probably would see more success than the monster they've created. I've been out of the C++ world for a while, but I hardly recognize the language anymore.
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