On Sat, 2025-08-09 at 21:30 +0200, Jens Maurer wrote:

On 09.08.25 21:06, Avi Kivity via Std-Proposals wrote:
A modern range-based solution would look like

```c++
   auto result = input
       | std::views::transform([] (size_t sz) {
           return std::vector<int>(sz);
       }
       | std::ranges::to<std::vector>();
```

This is still unsatisfying, as the lambda is not concise.

I disagree. The lambda is nice and readable.

See below.

Also, constructors in particular seem to have
std::initializer_list overloads occasionally,
but you can't perfectly-forward initializer lists.

Seems like that's a problem with initializer lists, not with the many facilities which use perfect forwarding.

Oh, and I haven't used mem_fn for ages, now that std::ranges
considers pointer-to-members invocable.

See, you prefer the conciseness. You wouldn't write a lambda to forward the call as you have an alternative.

Note, p3312 provides the ability to expose an overload set as a function object. If it's adopted, you'd write

auto result = input

| std::views::transform(&std::vector<int>::vector)

| std::ranges::to<std::vector>();

which I prefer to std::constructor.