←back to thread

The C23 edition of Modern C

(gustedt.wordpress.com)
415 points bwidlar | 1 comments | | HN request time: 0.242s | source
Show context
belter ◴[] No.41850897[source]
Important reminder just in the Preface :-)

Takeaway #1: "C and C++ are different: don’t mix them, and don’t mix them up"

replies(7): >>41850960 #>>41851047 #>>41851166 #>>41851693 #>>41853183 #>>41855660 #>>41857019 #
jasode ◴[] No.41851693[source]
>Takeaway #1: "C and C++ are different: don’t mix them, and don’t mix them up"

Where "mixing C/C++" is helpful:

- I "mix C in with my C++" projects because "sqlite3.c" and ffmpeg source code is written C. C++ was designed to interoperate with C code. C++ code can seamlessly add #include "sqlite3.h" unchanged.

- For my own code, I take advantage of "C++ being _mostly_ a superset of C" such as using old-style C printf in C++ instead of newer C++ cout.

Where the "C is a totally different language from C++" perspective is helpful:

- knowing that compilers can compile code in "C" or "C++" mode which has ramifications for name mangling which leads to "LINK unresolved symbol" errors.

- knowing that C99 C23 has many exceptions to "C++ is a superset of C" : https://en.wikipedia.org/wiki/Compatibility_of_C_and_C%2B%2B...

replies(4): >>41851853 #>>41852165 #>>41852449 #>>41856015 #
tialaramex ◴[] No.41852165[source]
The entire I/O streams (where std::cout comes from) feature is garbage, if this was an independent development there is no way that WG21 would have taken it, the reason it's in C++ 98 and thus still here today is that it's Bjarne's baby. The reason not to take it is that it's contradictory to the "Don't use operator overloading for unrelated operations" core idea. Bjarne will insist that "actually" these operators somehow always meant streaming I/O but his evidence is basically the same library feature he's trying to justify. No other language does this, and it's not because they can't it's because it was a bad idea when it was created, it was still a bad idea in 1998, the only difference today is that C++ has a replacement.

The modern fmt-inspired std::print and std::println etc. are much nicer, preserving all the type checking but losing terrible ideas like stored format state, and localisation by default. The biggest problem is that today C++ doesn't have a way to implement this for your own types easily, Barry illustrates a comfortable way this could work in C++ 26 via reflection which on that issue closes the gap with Rust's #[derive(Debug)].

replies(8): >>41852524 #>>41852543 #>>41853207 #>>41853365 #>>41854242 #>>41854396 #>>41855139 #>>41855859 #
wakawaka28 ◴[] No.41854242[source]
>No other language does this, and it's not because they can't it's because it was a bad idea when it was created, it was still a bad idea in 1998, the only difference today is that C++ has a replacement.

Hindsight is 20/20, remember that. Streams are not that bad of an idea and have been working fine for decades. You haven't named a problem with it other than the fact the operators are used for other stuff in other contexts. But operator overloading is a feature of C++ so most operators, even the comma operator, can be something other than what you expect.

>The biggest problem is that today C++ doesn't have a way to implement this for your own types easily, Barry illustrates a comfortable way this could work in C++ 26 via reflection which on that issue closes the gap with Rust's #[derive(Debug)].

You can trivially implement input and output for your own types with streams.

You appear to be a Rust guy whose motive is to throw shade on C++ for things that are utterly banal and subjective issues.

replies(1): >>41855426 #
PaulDavisThe1st ◴[] No.41855426[source]
What they mean is this:

     struct Foo {
       int a;
       float b;
       std::string c;
     };


     Foo foo;
     std::cout << foo;
with no extra code. It's called reflection, where the compiler can generate good-enough code to generate a character-stream serialization of an object without any human intervention.
replies(1): >>41856808 #
1. wakawaka28 ◴[] No.41856808[source]
I know what reflection is of course. C++ makes it easy to implement IO. If you're asking for a reflection-based solution with less effort, you are practically asking for zero extra code. Anyway, C++ does not yet have reflection but who's to say how anyone wants any particular data to be dumped? A default implementation is nice but less useful than you make it sound. In any case, there are libraries approximating what you described (usually with macros and stuff) and reflection is totally coming at some point.