C++20: An (Almost) Complete Overview - Marc Gregoire - CppCon 2020
Вставка
- Опубліковано 2 лип 2024
- cppcon.org/
github.com/CppCon/CppCon2020
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The technical work on C++20 was finished in January 2020, and is now being pushed through ISO certification.
This presentation gives an overview of (almost) all new features in both the language and the Standard Library. Some more exotic features will be left out. New language features include modules, coroutines, concepts, templated lambdas, constexpr changes, designated initializers, the spaceship operator, string literals as template parameters, feature test macros, conditional explicit, immediate functions, and more.
The second part of the session discusses the changes to the Standard Library. This includes topics such as ranges, atomic smart pointers, cancellable threads, a synchronization library, calendars, time zones, span, a formatting library, features test macros, and more.
The material is mostly the same as the "C++20: What's in it for you?" session from CppCon 2019, but it has been updated with the final standard. If you want a complete overview of all C++20 features, including references to other more deep-dive sessions at CppCon 2020 on certain topics, then this session is for you.
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Marc Gregoire is a software architect from Belgium. He worked 6 years as a consultant for Siemens and Nokia Siemens Networks on critical 2G and 3G software running on Solaris for telecom operators. This required working in international teams stretching from South America and the United States to Europe, the Middle East, Africa, and Asia. Now, Marc is a software architect at Nikon Metrology (www.nikonmetrology.com), a division of Nikon and a leading provider of precision optical instruments, X-ray machines, and metrology solutions for X-ray, CT, and 3D geometric inspection.
His main expertise is C/C++, specifically Microsoft VC++ and the MFC framework. He has experience in developing C++ programs running 24/7 on Windows and Linux platforms: for example, KNX/EIB home automation software. In addition to C/C++, Marc also likes C#.
Since April 2007, he has received the annual Microsoft MVP (Most Valuable Professional) award for his Visual C++ expertise.
Marc is the founder of the Belgian C++ Users Group (www.becpp.org), author of “Professional C++” 2nd, 3rd, and 4th Editions (Wiley/Wrox), co-author of “C++ Standard Library Quick Reference” 1st and 2nd Editions (Apress), technical editor for numerous books for several publishers, and regular speaker at the CppCon C++ conference. He maintains a blog at www.nuonsoft.com/blog/, and is passionate about traveling and gastronomic restaurants.
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Streamed & Edited by Digital Medium Ltd - events.digital-medium.co.uk
events@digital-medium.co.uk
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*-----* - Наука та технологія
Time Stamps
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2:46 - New Keywords
3:56 - Modules
9:03 - Ranges
15:00 - Coroutines
18:57 - Concepts
23:54 - Lambda Expression Changes
26:47 - constexpr Changes
27:54 - Concurrency Changes
33:33 - C++20 Synchronization Library
36:01 - Many more new features...
42:06 - Calendars & Timezones
45:27 - std::span
47:30 - Feature Testing Macros
48:36 - Version
49:12 - Immediate Functions - consteval
50:24 - constinit
51:19 - Class Enums and using Directive
52:07 - Text Formatting (std::format)
54:11 - Math Constants
54:31 - std::source_location
55:31 - [[nodiscard(reason)]]
55:51 - Bit Operations
56:34 - Small Standard Library Additions
Thanks for that informative video!
Thank you very much, very informative! Now I have to go rewrite all the code I have ever written, wish me luck!
C++20 is like a new language
no more headers and #include directives 🤯🤯
I personally never had issues before. int a = 5; has work just fine for DECADES.
Excellent talk! It really helps people like me get caught up with the latest developments in C++.
Very clear introduction to the new features of C++20. Thanks
Marc Gregoire, thank you very much. Your book is one of the best in C++.
Thanks, I'm glad you like the book :)
@@marcgregoire I took the Cisco entry level c++ course and finished it, do you think I'm a good candidate for the "Professional C++, 5th edition" book? I'm also a fullstack developer with Javascript/Typescript. Thanks!!
Excellent! Great overview towards c++20 finishing in one go!
Thank you much. Your talk was very comprehensive to follow.
Very nice walk-through. Thanks a lot.
Nice summary, found a few things that will I start to use immediatly.
Thank you for this informative session.
Nice presentation. IMHO Modules and concepts are the most helpful features.
Glad you think so!
This is amazing, so much good stuff!
Very useful overview about new features of c++20 with comparison c++17!! Great!!!
This was a fantastic overview of C++ 20. Thank you.
Thanks, an excellent overview of C++20!
Quite comprehensive! Thanks!
Great overview, thanks!
the speech is very informative. c++20 fabulous. i love it.
Great overview!
This is the language version of Christmas morning.
Thank you for this!
seems like C++ is getting even more functional
Great talk, thank you!
Excellent Talk!
Excellent
C++ 2O - C++ BORN Again ❤️
Thanks, good talk.
awesome !
Nice to see Rusts Iterators coming to C++.
good talk and good audio!!!!
Handful of new features in C++20 and eager to get my hands dirty and see how sweet/painful is it! Overall it was a long journey if we consider the whole transitions from late 90s.
This could be one of the most important talks in this year's cppcon
very comprehensive
constexprt strings, YES.
Good presentation of C++20. It has indeed many attractive new features (e.g. ranges; format; default comparison). Overall the C++ language still suffers from lack of standard libraries compared to e.g. .NET or JAVA; I hope they work on that in the future.
How does view::reverse work with infinite sequences like view::ints(10)?
first, view::ints(10) was wrong, it has to be "views::iota(10)".
But, you better limit your sequence when using something like reverse, for example using views::take(...)
So essentially C++ as some concepts from functional languages like F# and the pipeline processes of R?
Nice really handy for Data Science task in larger datasets or streams where python or R are too slow and SQL is too limited 👍🏽
Haven't done much c++20 yet but I do love concepts. Quite similar to typeclasses in haskell
Ranges looks somewhat similar to C# linq
It seems like the C++ standardization committee is trying to win over Javascript developers 😂
I took the Cisco entry level c++ course and finished it, do you think I'm a good candidate for the "Professional C++, 5th edition" book? I'm also a fullstack developer with Javascript/Typescript. Thanks!!
How to install C++ 20 on Red Hat Linux 8 ? I have installed the development tools on RHEL,. GCC and G++ also have been installed. How I can know if the version is C++ 20 ?
One day all code will be constexpr
Can you please make a cheat sheet with a summary of all the new features? Thanks!
I think that would be a rather big sheet, as the C++20 update is quite massive.
Is the coroutine example incorrect because it doesn't use `co_return` after the loop finishes?
No, the code is ok. It uses co_yield to return something to the caller. co_return is optional, if you don't need to return something at the end, you can just leave it out. Just like you don't need to write "return;" in normal function.
Think of python iterators you just need the yield in the example
So header Files are no longer needed to use anywhere or anytime?
Right, in new code, I would recommend to switch to using modules. It'll benefit your build throughput. But not all compilers are supporting it at the moment ...
re ranges: Finally! We have cast off the shackles of C (or at least one of many), where the "stylish" way to iterate over something was to use a begin and end pointers. Yuck!
Reminds me of Fortran.
Who will use all of these???
Does work on compilers happen at the same time as the standard is being decided?
Usually. There's generally several draft standards and item-specific documents that get published as part of the standardization process, and compiler vendors are often involved in the process anyway. Sometimes features are just standardizing common extensions the compiler vendors already offer, but I don't know how much of that applies to C++20.
Often yes.
If somebody knows about memory fences guarantees w.r.t. to synchronisation c++ primitives please let me know.
Did they fix std::set so we can have non const iterators again?!
It was deliberately broken in the past in case people change the key, preventing changes to any other part of the nodes data!!!🤪
Not a word about operator | for vector 15:00
With every release C++ is Approaching python semantics and syntax
54:55, how about a standard way of getting __PRETTY_FUNCTION__-like info ?
I'm not sure I understand what you want to do...
can I start c++20 without knowing c++???
49:33 - did you miss constexpr keyword instead of "const" on both slides?
No, if you make mm2 constexpr instead of const, then you'll get a compilation error. In my example I wanted to show that even though InchToMm() is marked as constexpr, that you are not guaranteed compile-time execution.
at 25:00, what is mean by T x { } ?
You create an object named x of type T and use "uniform initialization" with the result depending on T. If T is a built in type then it will be uninitialized. If on the other hand it is a class, then the object is created using the default constructor.
That just declares a variable x of type T and zero-initializes it.
Default value for T (default ctor or default 0 for int, float, double...)
hi, please i start to leaern c++ for the first time, so i start with c++20, i got a book for it, but am having a big problem, i can't have a compiler for it, most of the IDE i use doesn't support the c-++20 features like (import), please i need your help because now i stopped the studying.
i use these
VSC extension
codeblock
embarcadero
visual studio 2019
PLEASE HELP
please i need anyone help
How about not starting with the newest features that are not yet supported universally?
Just use C++17/14 - they are widely supported.
C++20 is now wastly supported (but not fully) by compilers.
The latest Visual Studio Preview has full support for c++20 modules.
Some good and some bad ideas here. My biggest issue is the growing complexity of C++ and having people understand your code when there are so many constructs in the language. Ranges make perfect sense for C++. Views make sense but using | for pipe-filter in addition to OR in other contexts is yet another opportunity for people to see code who hadn't seen that feature just get lost at what they are looking at. It's not necessary to have such features. We can already do filters as a sequence of function calls.
It's really annoying when they use the expression " Now with CXX you don't have to this, you can do this instead... " But why !😢
Is it only me who thinks that declaring variables like this makes it barely readable?
auto var { int { 10 } };
Thank Typescript for giving me better TypeC++20.
many of these ... topics.. ...ideas... ...concepts... so to say were already discussed in the circles of programming languages creators and of programmers in the last years...
in fact I find the D programming language has already all the benefits of those and has ALREADY today for example a better implementation of the module mechanisms...
only sad that it is not as visible as C++ ....
the problem with source_location is that in a real logger you would expect to forward arguments to std::format.. but having arbitrary argument count is not possible with the last source_location param.
nice summary tho, i enjoyed. Thanks!
You still can forward it to std::format as it ignores unused args. Or you can provide a specialization (I think) that will do nothing.
It's a great lecture.
Tho I don't really like computer science. It's all about keeping making new concepts and names for people to learn and make simple stuff more and more confusing to keep their job secured.
So you would like to keep developing computer science without making new concepts, or you accept making new concepts but you would like them to be left unnamed? I guess you have similar criticism for, say, medicine, chemistry, physics, etc.?
C++ 20 just clusters the c++ landscape. I just don't get it why the committee is constantly adding language features that have no impact on performance. I mean, no one comes to C++ for its "cool" language features.
C++ 23: pointers are removed, no data types- it's basically Python! That's my guess.🙄
Well, that's not gonna happen for sure.
C++ borrows the idea based features from Higher Level Languages, but using Dynamic Type System like Python, will make it slow like Python :)
Is it going the other direction; i.e Python and JavaScript getting type annotations?.