In what benchmarks?!?
Memory footprint will be smaller on C without using C++ abstractions. Which is important for embedded systems.
Yes. But even C was considered too slow for something like a Motorola 68000 back in the day. Of course it's possible.
Besides, C++ can be just as performant if you ignore a huge proportion of its language features and abstractions, but what's the point then? Just use C.
And this is precisely why embedded engineers do so.
Go figure.
What has made relevant was the rise of FOSS UNIX clones and the GNU guidelines for using C.
All major desktop OSes were already on the path of adopting C++ frameworks. BeOS, Windows, OS/2, Mac OS.
Thankfully C has been shown the door on Apple, Google, Microsoft, Sony, Nintendo and ARM platforms.
Others will follow.
FOSS UNIX clones and old time embedded developers are the only ones keeping C relevant.
Your cons:
- Virtual functions. Don’t use them if you don’t want to incur an extra indirection.
- STL. Don’t use it if you don’t want to.
- Large binary size. Don’t spin up hundreds of template instances, problem solved.
- No RTTI? Literally a compiler switch away.
Some pros:
- constexpr
- true type safe generic programming (at the cost of code size if you get crazy with it and like TMP)
- type safe no-overhead containers (std::array, std::tuple)
- RAII ownership semantics (I.e. std::unique_ptr)
- Can still emit a C ABI
- Multi-paradigm at a language level, rather than procedural with other paradigms bolted on ad-hoc
The reason C++ (IMHO) is always a better choice than C is that if you don’t want to incur the cost of feature X, drop down to how you would do it in C and it works exactly the same and you can still use the zero-cost C++ features that will never land in C.
But it is not true for embedded systems. And the industry disagrees too, and continues to use C because of this.
What resource constrained embedded systems even exist? Fucking lightbulbs run JavaScript these days. SmartCards have been running Java for 20 years. What is the actual market you're so up in arms about that you think is choosing C on technical merits instead of purely inertia? What is this "performance constrained embedded" market to you?
The very definition of embedded systems?
I would say it is more much likely the many folks who work on embedded systems in C are right and do so with technical merit. And it is much more likely that it is you who is wrong. Which is quite clear as someone who seems to advocate using JS on embedded hardware for serious tasks. A detail that is seriously amusing in its own right.
Are we talking about PICs with 4KB, or ESP32 that would run circles around the Amstrad PC 1512 that I used to play Defender of the Crown on?
A system that already had quite a few high level programming languages available for us to learn programming on.
Ah maybe we are speaking about my Visa card running a set of tiny Java Card applications on 256KB, to handle my authentication processes at POS.
Microcontrollers got a lot faster and more powerful over the years. What problem in that space kept up with that speed advancement? Who is paying for hyper-optimized C/asm code instead of just spending an extra $.50 for a dual-core 240mhz ESP32? And who is doing that decision and has decided C is somehow faster than C++?
> Which is quite clear as someone who seems to advocate using JS on embedded hardware for serious tasks.
I never advocated for it. I said it happened.
https://os.mbed.com/javascript-on-mbed/
On Samsung's SmartThings embedded devices
https://smartthings.developer.samsung.com/docs/index.html
SigFox customized IoT solutions
Or on the other side from ARM mbed's offering, a beefy ARM 580 MHz with 96 MB (RAM + Flash), using JavaScript alongside Rust.
Now if your only definition of embedded are constrained micro-controllers that aren't even able to cope with standard ISO C89 without having additional proprietary compiler extensions, then naturally everything else are just miniature desktop computers.
Meanwhile some forward looking companies keep on delivering innovative products.
I don't think I ever gave a definition of an embedded system, but you can quote me to prove me wrong. A PC embedded in a slot machine for instance can also be called an embedded system. A more important distinction is whether the system must run in real time or not. And you can have a beast of a microprocessor and you will not be able to do low level real time processing with it in javascript.
RAII is baad for performance. Really bad. It's an OOP programming style that can be used to glew a few high-level constructs together. But if you use it on the lower levels, you will miss out on a lot of (systemic) optimization possibilities, because RAII gives you piecemeal construction/destruction pairs.
constexpr/generic programming might have a few nice applications, but in most places they're used without a real need (from what I've seen), while leading to extremely slow compiles. (Those in turn lead to longer turnaround times, worse program quality, worse efficiency...).
std::array, like std::vector, is some nice sugar compared to the C primitives, but if you use them at API boundaries you will get bad coupling effects.
The C++ programmers that I look up to all write basically C with maybe a few select C++ features. Many never write "class" and never include C++ headers. Some just write plain C.
People do change their mind.
Yes, I do know that HPC# is somehow constrained, yet even as C# subset, it still supports quite a few features that Mike wasn't so found of having to deal with in C++, as per his CppCon talk.
It seems he's still working on the same ideas and themes that his (in)famous talk from CppCon was about. Check this out, for example: https://twitter.com/Icetigris/status/1116771416072806401 . As far as I'm concerned, that's basically C.
Btw, have you updated your idea of ECS and "Data-oriented design" in the meantime? (Man, I've really started to be annoyed by this buzzword!)
Btw for extreme data-oriented programming you might actually be able to afford GC, provided you have value-type compound types like I think C# has. That's because there are only a few allocations around. Not that GC matters in this case - you don't free the global tables anyway except maybe at the end. And bounds checks might be easier to optimize out (?).
More importantly, it's not easy to tell when you're going to hit performance issues with C++. You need an obscene amount of knowledge of both the language as well as hardware to get a sense of what to use to match C performance.