[wolf550e]

If the individual cycles don't matter, you can use a safer language than C++ which compiles faster and provides more static and dynamic guarantees. If you choose C++ for a new project in 2017 it's because you need all the cycles and would have chosen assembly if you thought you could write the asm fast and cheaply enough.

[nightski]

First of all, the world isn't that black and white. Second, the advantage of C++ is that you are not forced to use these abstractions. You can pick and choose when to use them and pay the performance penalty.

[wolf550e]

For the parts of the codebase where you can use abstractions that have runtime costs, you can also choose a safer language that imposes similar runtime costs. I bet it would be easier to write maintainable code in the safer language than in the version+subset of C++ on which your team agrees.

For the parts of the codebase where you count cycles, you often want to carefully lay out the data and then use hand coded SIMD. Possibly use a specialized code generator that writes the SIMD asm for you, with less chance of error. If you can't do SIMD, I would just use C, but use a safety-critical code standard for the C part.

Existing codebases and existing investment into learning C++ arcana complicates these decisions, but I truly believe C++ is not worth it for new projects.

[fsloth]

"I truly believe C++ is not worth it for new projects."

So what would you use if the constraints for the project are of the usual C++ kind? I.e. language has industrial support, proven toolchain, loads of potential candidates who can write the language, the code will compile 20 years in the future, can tightly integrate with a gui ... etc. Honestly, if there is a better language where I percieve C++ to be the best language I would dearly like to know. Half of the reasons I use C++ have nothing to do with the language itself but of the modern computing ecosystem.

[pekk]

Many other languages have industrial support, a proven toolchain, and are known by a lot of candidates: Java, C#, modern C... this is if we restrict ourselves to only the most popular languages with compile-time type enforcement, which is fairly arbitrary.

It's okay to admit that you like C++, it's what you know best, and that it's not unsuitable for the things you want to do. The same as someone else says that about F# or Lua.

[blub]

Yes, there are many alternatives. None of which offer the same advantages as C++. If one can swallow the costs, by all means, be my guest and use whatever language you want, no one will care much, unless you end up using 13% CPU rendering a blinking cursor.

But that's not what you and others are arguing here... instead you're arguing that there are no reasons to use C++ and one should use other languages instead. Which is pure nonsense.

[wolf550e]

It would really depend on what the project is (3d shooter game vs database server vs high frequency trading). But I think many projects can be broken into two parts:

One is a limited number of "computation kernels" (processing packets, processing transactions, computing a photoshop filter) that need to be very fast but can be carefully generated/handcoded in C or SIMD asm or whatever that has very simple behavior/API, for example it should not allocate memory.

The other part is the complicated part that has all the complex behavior (a lot of code, changing business requirements, opportunity for abstraction) that configures the kernels and feed data into them and interacts with the user and the network but takes a small part of the CPU time.

The second part must be organized so that it will not inhibit the first part in any way, so that means the second part can't use a language that won't let you layout stuff in memory in exactly the way you need or that has poor cffi performance.

The second part can be done in something as slow as cpython! (though it doesn't have to be quite that slow).

[blub]

You started with an absolute statement "C++ should not be used in 2017 for new projects" and in the following comments slowly but surely admit that the above statement is false.

It would be simpler next time to just state that C++ is not a must for all software. But we already know that, so maybe the whole discussion can be skipped.

[wolf550e]

You are putting words in my mouth. I did not say "should not be used". I wrote about my option and what I do. I did not mean this advice applies to everyone in every situation.

I think your approach is "default to C++ because of very broad support, write the cold code and the hot code in C++, optimize the hot code" and implicitly you also say "and damn the security and maintainability implications".

My approach is "use the safest and most maintainable language for all code that can tolerate the performance impact", so I would prefer to write everything in a higher level language than C++ and optimize using cffi, asm, etc. only the inner most loop.

Maybe modern C++ can overcome the weight of backwards compatibility and create a truly modern subset that is as safe and as pleasant to work with as newer languages. Then your approach would definitely be better. But I don't think we're there.

For example, I think of things like a web server, where the AES-GCM has to be assembly, the HTTP parser should be generated by a special tool and the rest should be in a memory safe language to avoid Cloudbleed. Can modern C++ be that memory safe language? If yes, I'm wrong.

[blub]

Your whole argument falls apart when one considers that performance needs aren't split just between SIMD + careful data layout and anything goes.

C++ isn't used only for generating the fastest possible code, but also to generate code with predictable performance, code that is default-fast and code that can be optimized without the fear of having to change programming languages to reach a performance goal.

[pekk]

And the disadvantage is that you have to pick and choose them after learning about all of them, and you have to deal with the choices made by whatever other code you have to work with, and you have to reason about all the combinations. For most tasks, this is overkill, which is why C and languages other than C++ persist even though C++ has everything.

[xwvvvvwx]

I think the point is not that the abstractions have some cost, but that the cost is higher than it needs to be.

I would also agree that pure performance and deterministic memory management are the two main reasons to use c++ for a new project nowadays.

[blub]

I've seen this kind of misconception before and it should be corrected. Your premise is wrong, there are other reasons to pick C++ besides performance:

* it's platform-native on the major platforms and many others

* it's an international standard and has excellent backwards compatibility. i.e: it's not controlled by some corporation and it's very unlikely that a 2v3 Python-style fiasco would happen.

* it has a huge ecosystem. The only comparable ones are Java and maybe C#, but while there's overlap, each ecosystem has its focus. Java's is focused on the back-end and enterprise development.

* it's a flexible and powerful language

* it's basically the default option in certain domains