On 10/11/2024 12:02, Jonathan Wakely wrote:
>
> On Sun, 10 Nov 2024, 10:54 Jonathan Wakely, <cxx_at_[hidden]> wrote:
>
>
> On Sun, 10 Nov 2024, 10:06 André Offringa via Std-Proposals,
> <std-proposals_at_[hidden]> wrote:
>
> Dear all,
>
> I'd like to float the idea to make it possible to construct a
> std::complex and a std::vector uninitialized. [..]
>
> std::ifstream file("myfile.bin");
> std::vector<char> buffer(buffer_size);
> file.read(&buffer[0], buffer_size);
>
>
> This is exactly the use case that string::resize_for_overwrite
> solves. I think there is already a proposal to add a similar
> function to vector.
>
> The committee has seen lots of proposals for a tag that says to
> leave a container uninitialised, and has always decided we don't
> want that because it's too error-prone and risky.
>
>
> Actually I misremembered, there was support for a tag type, but
> resize_for_overwrite was preferred for string. See the discussion in
> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2021/p1072r10.html#alternatives
>

Thanks for the response and the link, nice to see there seems support.

Has the complex type ever been mentioned in such discussions? Imho it is
currently a more fundamental problem that can't be worked around. It
might be simpler to solve since there's no allocator involved. For
complex I also don't see a way around a tag, which might be another
reason to introduce such a tag.

Also, do you happen to have a link to report where the discussion for
vector takes place?

I had seen the method name resize_and_overwrite() but I had not realized
it was intended to solve this problem. It doesn't have an easy name...
But if vector had it, it would solve the problem I have. It's imho not
as readable as a tag constructor but still a good solution.

Regards,
André