I may be in no position to criticize any programming language, but hey — we were told to be bold and controversial so here I am with Yet Another C++ Rant.

C++ is a terrible language. I’m pretty sure all of you already know C++ Frequently Questioned Answers — it’s a bible of C++ quirks, a must-read. C++ claims to be multi-paradigm; procedural, object-oriented and generic. But it fails on all levels — I mean, have you ever tried to implement delegates in C++ without external libs? Or STL containers, they should be so superior to C# generics due to compile time evaluation, but have you ever seen assembly generated? And I’m pretty sure that the whole metaprogramming idea inspired many folks to build a CPU inside Minecraft.

But to be fair: a lot of good software was build and shipped with C++ (or not entirely crippled by C++ as FQA would state). So perhaps people may find use of various C++ features, depending on personal taste. But the real problem with C++ features is an amount of them. There are tonnes and tonnes of those features, some widely known and some remaining in the dark, waiting for years to shoot your foot off. And C++0X is only going to make things worse. I greatly admire people behind C++ compilers. Those guys are real heroes. But I’d love them to improve optimizations, not some bizzare and/or creepy features that are likely to explode when used together. If I didn’t care about performance, I would not use C++ anyway, right? But the sad fact is that a lot of C++ features prevent optimizations in direct (e.g. side effects you don’t care about) of indirect (because compilers are getting extremely complex) ways.

And you can’t expect people to know all those tiny little features of C++. It can be expressed like this:

(∀ x ∈ C++ programmers) (∃ ε > 0) x is the only one who knows some bizarre C++ feature around radius ε

And so, to keep people sane and deliver some software, most companies that still use C++ put a lot of restrictions, mostly “don’t use …” (exceptions, RTTI, non-container templates, whatever you hate). In extreme cases, only “C with classes” is left. Not that it’s bad, it’s something I use personally (BTW: usage of C++ features can be perhaps measured in ratio of Release/Debug performance — and I know some games in which Cornell box level is just a little too much for debug build). But the compiler doesn’t know that we disrespect that “bad part” of C++ and still have to do its job.

Any alternatives to C++? It’s not easy. The sad fact is that most languages have compiler/library/IDE issues. D haven’t ever gained attention, C# is not crossplatform and Java is <insert your favourite joke here>. At the moment there is no easy replacement or at least I don’t see one.

But I keep my fingers crossed for LLVM. LLVM is a complete compiler infrastructure, but the most interesting part is backend: optimizations and generation of machine code (either static or JIT). Our job is “just” to make a front-end for our language, which is quite simple for simple languages (especially using tools like Flex/Bison). But why limit yourself to one language? I can think of following scenario:

  • “main” language, similar to “C with classes and whatever we really need” used for most engine/game code
  • “computational” language, similar to shaders (see my previous post here)
  • “gameplay” language, similar to Lua

The greatest benefit I see is that using uniform infrastructure we could glue those pieces of code without additional layers of wrappers (like in typical C++&Lua code). Another win is uniform debugging using one tool only (LLVM IR may contain standardized debugging information). And of course another huge advantage is an ability to fine-tune each language to specific needs:

  • “computational” language doesn’t need to have classes
  • but must have robust vector/matrix support
  • “no side effects” functions and compile-time optimizations using this
  • SSE/Altivec  is mandatory
  • GPU/SPU support would be cool, too (although some folks would be very unhappy not having to manually adjust SPU assembly)

On the other hand:

  • “gameplay” language could implement a number of Lua-like features
  • like functions as first-class citizens
  • maybe also coroutines
  • garbage collected, duck typed? a lot of options here

But wouldn’t maintaining three different languages be harder than just one? Well… if you need a language suitable for any job with a bunch of features, I can’t help noticing that there is one already, yet I think you already know that I don’t like C++ very much. And wouldn’t maintaining any number of custom languages be harder than just shutting up and continuing to use C++? Honestly, I don’t know. While C++ is horrible as a language, it has excellent IDE/debugger/libraries/etc support. This would be very tricky to fight and you probably won’t get far without some kind of C/C++ compatibility in “main” language. However, I’d still give it a shot.