On Saturday, 5 October 2019 at 04:07:45 UTC, Meta wrote:
I'm not sure if you're aware, but funnily enough, I also wrote
an article[1] on std::variant vs. the D alternative that
references Matt Kline's article on std::visit. It seems we're
really making getting our money's worth from his article.
I really enjoyed this - I think you're right in that it comes
down to the complexity of implementation, and I suspect that
C++ forced the developers of std::variant to choose between a
usable API (usable, not good) and performance.
I remember seeing your article when it went up on the D blog.
It's a great illustration of how things that are complex in C++
are often easy or even trivial in D.
Some of the commenters on reddit brought up boost.variant2 and
mpark::variant as alternative C++ implementations that generate
the same code as C. So it's clearly *possible* for C++ to get
good performance on this. It's just that in C++, you have to work
really hard for it, whereas in D, it's so easy you'd have to work
harder to get it wrong.
