P2881 proposes a new way to build iterators, similar to generators but with less performance overhead and better nesting (and hence composability):
struct generator123
{
auto operator()(auto&& sink) const
{
std::control_flow flow;
// With P2561: sink(1)??;
flow = sink(1);
if (!flow) return flow;
// With P2561: sink(2)??;
flow = sink(2);
if (!flow) return flow;
return sink(3);
}
};
int main() {
for (int x : generator123()) // x iterates 1, 2, 3
{
std::print("{}\n", x);
if (x == 2)
break;
}
}
While the benefits are undisputable, it's quite verbose without P2561 and I feel C++ is starting to have too many different iterator models.
What do you think?
One of the authors has a nice presentation about pitfalls of ye olde for loops, which was probably a big motivator too: https://www.youtube.com/watch?v=95uT0RhMGwA
Regular expressions are great and can always be matched in linear time with respect to the input string length.
The problem is that JS standard library RegExps aren't actually regular expressions, but rather a much broader language, which is impossible to implement efficiently. If RegExp switched to proper regular expressions, they would match much faster but supporting backreferences like /(.*)x\1/ would be impossible.