C++17 - The Best Features - Nicolai Josuttis [ACCU 2018]

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C++17 - The Best Features - Nicolai Josuttis [ACCU 2018]

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Күн бұрын

C++17 is out for a year now and at least partially supported by Clang, GCC, and Visual Studio. While C++ is no revolution and changes the style of programming (as C++11 did), it is a remarkable collection of many many features both in the core language and the library.
Time to list the best and most useful improvements C++17 (in my opinion) provides.

Пікірлер: 63

5 жыл бұрын

Every update makes C++ easier & more comfortable. Thanks a lot for your introduction speech!

@MN-sc9qs 5 жыл бұрын

Getting closer to Python!

@saminchowdhury7995 4 жыл бұрын

Won't the compilation take longer tho?

@celticwinter 3 жыл бұрын

@@MN-sc9qs Yes, and Fortran is getting closer to LaTeX. What is this even supposed to mean?

@yackawaytube 4 жыл бұрын

Morgan Stanley still has the best C++ programmers out there, under Stroustrup's leadership. BTW, he could have easily explained transform_reduce as map-reduce

@DJTrulin 7 ай бұрын

I have not touched C++ since before C++11 (!) and have learned my habits from modern java, python and now rust. Using this video as a springboard so I can quickly learn c++ for an interview... It's going to be an intense study, but I think I can try to map the type-safe & memory-safe attributes of rust by adopting these new language features and some type of coding style to recreate ownership principle in C++.

@tourdesource Жыл бұрын

This was super interesting, thank you Nicolai.

@ramkrushnashelke5894 4 жыл бұрын

its beauty...

@MohamedAli-nr2dr 5 жыл бұрын

Great job gentleman

@michaelchoi8247 5 жыл бұрын

beautiful.

@jmelas 6 жыл бұрын

awesomeness

@JiveDadson 6 жыл бұрын

I love inline vary abbles.

@Schcarraffone 3 жыл бұрын

not that fun in st peterburg right??

@DavideLibenzi 7 ай бұрын

std::variant may have its use, but the argument about replacing normal vtable inheritance is weak. std::unique_ptr + std::make_unique or std::shared_ptr + std::make_shared remove the worry of freeing things. Sure, you make allocations, but unless the object is really trivial, you may have others within the object constructors that offset the saving. If sizeof(A) >> sizeof(B) in std::variant the size will be the one of the biggest object, within a vector (for an implementation which avoid allocations by using std::variant self storage). There is a local vtable generated by the compiler upon std::visit (check with godbolt), and obj->draw(...) is MUCH cleaner than the std::visit dances. There might be cases (very small, trivial objects ... or inlined object method calls within std::visit) where std::variant might be useful, but IMHO the argument of standard vtable based inheritance replacement is weak.

@RoyBellingan 6 жыл бұрын

How can I press like 12 times on this video ?

@ian3084 4 жыл бұрын

What happens if you have a static inline variable in a header, used in 2 libraries or a library and an app?

@ACCUConf 4 жыл бұрын

Your comment has been forwarded to the speaker :)

@ian3084 4 жыл бұрын

@@ACCUConf Oh thank you:)

@yuehuajia3176 6 жыл бұрын

wonderful

@dillip4572 2 жыл бұрын

aweome, thanks champ :)

@ACCUConf 2 жыл бұрын

Glad you liked it!

@Terszel 4 жыл бұрын

The problem with variant is that when I make a container of base class instances, usually it is either a) derived classes I do not know of or b) other templatized containers. Of course I am not going to forward specify a discrete set of those templatized containers so this variant semantics is 100% useless in my cases. I still have to deal with copy pointer mistakes and use after free issues and variant wont help

@tourdesource Жыл бұрын

Well, he does specify that std::variant is supposed to be used with closed sets. Perhaps not the tool you need, but a good tool nonetheless.

@eduardofernandezdiaz5264 4 жыл бұрын

Did this new update to C++ caused any changes to its performance?

@alexanderdon215 2 жыл бұрын

no operator new for vector elements.. does it create a variable on the stack or in the heap?

@kipu44 8 ай бұрын

In the heap. The vector is still created in the heap but it contains its elements directly, rather than pointers to the elements, so there is no need to call new for each element.

@hl2mukkel 6 жыл бұрын

Good talk!

@shahmiBro1 5 жыл бұрын

why don't you use Lisp? and as mentioned by Andrei Alexandrescu in his talk from MeetingCPP, fix the if constexpr for the sake of humanity;

@Bbdu75yg Жыл бұрын

Wow

@tomnichlson 6 жыл бұрын

How is variant/ visit better than smart pointers?

@petermuller9518 6 жыл бұрын

I would not say better, but using variant allows you to use the stack instead of the heap at the expense of using a compile time fixed set of types

@llothar68 6 жыл бұрын

This is faster because it saves 1 indirection and lots of memory for the shared pointers (at least 48 bytes per item on 64bit). Also the class hierarchy gets less dependencies which might be nice or irrelevant.

@jomunoz 5 жыл бұрын

In addition to what Lothar said, also in the variant example the elements are faster to transverse since the elements (Circles and Lines) are next to each other. In the pointer example, the vector only contains the pointers, the objects they point to can be anywhere in memory.

@Evan490BC 5 жыл бұрын

@@llothar68 I think viewing those in terms of stacks and heaps is a very low-level point of view here. Variants is an attempt at providing sum types in C++. Smart pointers is an attempt at providing ownership semantics (similar to Rust's), a crude version of linear types.

@llothar68 5 жыл бұрын

@@Evan490BC Sorry i'm too old for this type esoteric bullshit. I stopped when they started to call simple down casting (to void as an extrem) type erasure. Everything in computers is explained much much better when you go to assembler level and then explain it from there. SmartPointers is not ownership, it's reference counting and nothing else. The ownership semantics are just one use case for it. I can put two different reference counters on the same object and provide an invoked when reaching zero that might do something totally different and it would still be legal C++. I think this is the main reason why people today can't program anymore.

@evandrix 6 жыл бұрын

public link to slide deck?

@ACCUConf 6 жыл бұрын

All slides have been uploaded to the ACCU conference website under the 'sessions' tab.

@evandrix 6 жыл бұрын

conference.accu.org/2018/sessions.html ? i don't see any links to PDFs...

@ACCUConf 6 жыл бұрын

Sorry my mistake, they are being added to the schedule page: conference.accu.org/2018/schedule.html Not all have been uploaded yet, check back in a couple of days and they should all be there

@llothar68 6 жыл бұрын

C++ is too damn difficult

@EDANAiRoNY1 5 жыл бұрын

no its so easy

@Knuckler 5 жыл бұрын

@@EDANAiRoNY1 you didn't gawk at the variant example? You must be a c++ expert.

@deanroddey2881 5 жыл бұрын

@@Knuckler I feel like I'm taking crazy pills when I listen to C++ modernists sometimes. I mean variant is possibly the biggest single reason that OO was invented. Apparently they don't remember this. Variant is nothing but a glorified case statement. And one of the reasons OO was invented was because of exactly that, that you ended up with a bunch of case statements. And every time you add some new functionality, you have to go to every such case statement and figure out, what do I need to do for each of these cases. Unless it's very simple and unless it's a completely internal detail, it's crazy because you know have client code having to make these decisions. And, on top of that, he turns around and creates a class hierarchy of functors to get around the fact that he didn't create a class hierarchy to begin with, AND makes it all templatized so that it isn't explicitly typed. It's like some sort of bad joke to see if we get it.

@EgD996 6 жыл бұрын

Great features! The only problem is it is too late!

@mcbernnard4303 5 жыл бұрын

It's better than nothing. C++ is the King of Programming Languages.

@eminqasimov3398 5 жыл бұрын

😂😂😂yeah agree, i plan to learn Rust instead of c++ for boost my web projects.

@a314 6 жыл бұрын

Good list.. good to see C++ catch up with D language.. but still can't beat that

@llothar68 6 жыл бұрын

Wrong. Two words: TOOLS and LIBRARIES

@VictorMartinez-zf6dt 6 жыл бұрын

C++ is just playing catchup and adding complexity to the language. So glad languages like Rust and Go are going to replace it soon.

@Knuckler 5 жыл бұрын

"Soon", meaning in the next 20 to 30 years, right?

@Evan490BC 5 жыл бұрын

Not Go. Go targets a different space. Rust, maybe.

@joestevenson5568 5 жыл бұрын

yeah, soon.....

@beardninja5029 5 жыл бұрын

I wouldn't bet on Go but Rust? definitely.

@cipherxen2 5 жыл бұрын

@NycroLP 5 жыл бұрын

c++ is such a mess

@NotBroihon 5 жыл бұрын

Just because it goes over your head doesn't mean it's a mess.

@gast128 2 жыл бұрын

Agree. To name a few: std::vector{1} vs std::vector(1); forwarding references; two phase lookup and the iostream library. I still prefer C++ over any other language mainly due to its low overhead.