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points by amluto 4 days ago | 0 comments

I maintain a codebase that I’ve migrated from C++98 to C++11 and all the way to C++23 and even a bit of draft 26 (the latter for some minor library improvements). Few things made me quite as happy as moving from using SFINAE to using requires clauses and concepts.

(IMO the single best improvements over the years have been atomics and maybe variadic templates.)

[–] jandrewrogers 4 days ago

I think you are right to position atomics and variadic templates as among the most consequential features of C++ in the last couple decades. It made an enormous number of things possible.

One thing I give the C++ feature gods credit for is recognizing material deficiencies in systems languages and unapologetically trying to fill those gaps starting with C++11. The addition of atomics, strict variadics, constexpr, lambdas, concepts, lifetime annotations, etc has been transformative for C++.

[–] aw1621107 3 days ago

> lifetime annotations

Say what!?

[–] throwaway2037 4 days ago

    > the single best improvements over the years have been atomics...

Of course, libatomic and friends have existed for a long time. Real question: Do you feel that the standardisation of atomics within the C++ base library is a material advantage over using libatomic? Also, maybe there are atomic APIs in the C++ base library that are better than libatomic. If so, please kindly share an example or two. I would like to learn more.

EDIT

I forgot to give a hat tip to your big upgrade from C++98 to C++23. In some projects, that can require an enormous amount of effort! Can you share a "stories from the trenches" that were difficult in that upgrade?

[–] bluGill 4 days ago

Standards work best when they can take a bunch of existing slightly different implementations and pick the best of them all, with input from people who understand the compromises, and with input from the real world experience of the different ways those compromises work out in the real world.

Atomics could work that way. However many other things cannot - we knew modules were a good idea, but they are a everything on a project must use them before anyone can benefit and so they were forever doomed to not be in widespread use until there is a standard. Even today we see adoption is slow because while there is a standard that works everybody is waiting on some other part to adopt before they can get any benefit. (and those who need to go first see the least benefit), but there are signs that things are moving.

[–] pocksuppet 4 days ago

libatomic is a GCC implementation detail that implements atomic math operations that are not available on the target platform by using non-atomic math and compare-exchange. Are you sure that's the one you mean?

[–] Shorel 4 days ago

I want to read your blog describing these experiences.