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Comment by makz | Hacker News Reader

What does “Classic C++” mean?

This library is nicely concise, and the code is mostly readable (although there are some non-obvious tricks that could be better documented).

The Makefile could need some work:

  json_test.cpp:360:23: warning: missing terminating '"' character [-Winvalid-pp-token]
  { Json::success, R"({
                        ^
  fatal error: too many errors emitted, stopping now [-ferror-limit=]
  9 warnings and 20 errors generated.
  make: *** [json_test.o] Error 1
  % c++ --version                   
  Apple clang version 15.0.0 (clang-1500.1.0.2.5)
  Target: arm64-apple-darwin22.6.0
  Thread model: posix
  InstalledDir: /Library/Developer/CommandLineTools/usr/bin

Compiling direclty with

  c++ --std=c++11 -c json.cpp

works fine, though.

There are approximately three major dialects of C++. They are distinguished by major changes in what idiomatic code looks like, enabled by the addition of core features to the language that made it more efficient and type-safe to express many things.

The era of so-called “modern” C++ started with C++11, which was a radical reworking of the language. All prior versions of C++ are “legacy” or “classic”. Idiomatic code in “modern” and “classic” dialects almost look like different languages.

C++20 arguably marks a new dialect break but it doesn’t have a colloquial label to distinguish it from “legacy” and “modern” AFAIK. Idiomatic C++20 looks pretty foreign from a C++11 perspective (but is unambiguously an improvement).

This library supports building with C++11. I haven't tried compiling it with an older standard, but I imagine it might work. One thing I like about the C++11 compilers like GCC 4.9 is they build code magnificently faster than recent editions. See https://x.com/JustineTunney/status/1795427808631758936

> This library supports building with C++11. I haven't tried compiling it with an older standard, but I imagine it might work.

I believe it does require C++11, due to std::nullptr_t and r-value references (&&), but that might be it. It's not a show stopper though since everyone should have a c++11 compiler now (even Ubuntu 14.04 LTS, which still has paid support I believe).

> One thing I like about the C++11 compilers like GCC 4.9 is they build code magnificently faster than recent editions

Kind of reminds me of gcc 2.95 which people kept around for the compiler speed. They would use gcc 3.x for the warning support and then compile with gcc 2.95 after fixing the warnings :).

Yes they'd be very trivial to remove locally. It might also be nice to have #ifdef statements around them like we're already doing for std::string_view. If we consider that many big name C projects like curl are still on C89 then there's surely got to be people still out there using 2000's era C++.

> It's not a show stopper though since everyone should have a c++11 compiler now (...)

I think the point of pointing out it's C++11 is that it's not "classic C++" as it's using "modern C++" features. Thus it's a mystery why it would be referred to as classic C++.

Just because I included an rvalue constructor doesn't make it C++11. This library was originally written in C. It hasn't changed a whole lot since Gautham and I originally wrote it: https://github.com/jart/cosmopolitan/blob/master/tool/net/lj... I feel perfectly comfortable calling C++11 "classic" or even "baroque" compared to what people are doing with C++ in 2024. However if you disagree with me, and feel that classic means C++03, then I've made certain that your preferences are supported by this library too. Just remove the rvalue and nullptr_t constructors. I'll probably add #ifdefs soon to automate that too.

> Just because I included an rvalue constructor doesn't make it C++11.

Actually, it does. I mean, does it compile when you pass -std=c++98?

> This library was originally written in C.

Doesn't matter. If it uses C++11 features, it's C++11.

> I feel perfectly comfortable calling C++11 "classic" or even "baroque" compared to what people are doing with C++ in 2024.

Irrelevant. You can go the Humpty Dumpty way as far as you want to go and call anything any way. It doesn't matter. If you use C++11 features, it's C++11. If it's C++11 then you're discussing modern C++. You don't need to use all bells and whistles to quality.

I don't think it's entirely accurate. "Modern idiomatic C++" was a thing already before C++11 - that would be the kind of code that heavily used the standard library and especially STL containers, iterators etc (but also stuff like auto_ptr etc; and yes, for all its flaws, it was actually used).

And don't forget that C++03 TR1 also added a bunch of very useful stuff - most notably, std::shared_ptr and std::function. And, of course, Boost has been a thing long before C++11, filling many gaps for "modern C++" projects of the time.

"classic C++" from that perspective is C++ written more or less Java-style.

"Classic C++" and "Modern C++" refer to the language before and after C++11, respectively.

Some of the key differences are use of standard library and its containers, smart pointers, and other language features that look less like C. In this specific library, this refers to some of the techniques like bit manipulation, manual memory management and string parsing, and using things like enums to improve speed and reduce complexity.

An example of a more robust (but still "classic") library would be something like https://github.com/Tencent/rapidjson.

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