On Thu, 15 Feb 2024 at 11:12, Marcin Jaczewski <marcinjaczewski86_at_[hidden]>
wrote:

> czw., 15 lut 2024 o 11:23 Jonathan Wakely via Std-Proposals
> <std-proposals_at_[hidden]> napisał(a):
> >
> >
> >
> > On Thu, 15 Feb 2024 at 09:54, Tiago Freire via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
> >>
> >> And what exactly would this do?
> >
> >
> > Exactly what the standard does for subrange::size_ in
> [range.subrange.general]
> >
> >
> > make-unsigned-like-t<iter_difference_t<I>> size_ = 0; // exposition
> only; present only
> > // if StoreSize is
> true
> >
> >
> >
> >
> >>
> >> -----Original Message-----
> >> Subject: [std-proposals] Requires-clause for data members
> >>
> >> Has there been any discussion of requires-clauses for data members?
> >> Something like:
> >>
> >> > template<int N>
> >> > struct numbers {
> >> > int x requires (N >= 1) = 0; // leading
> >> > int y requires (N >= 2) = 0; // trailing };
> >>
> >> It seems grammatically possible if you mandate parentheses, and it
> would certainly help people reduce the use of partial specializations in
> these places.
> >
> >
> >
> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3613.pdf#section.5
> has some discussion of an earlier idea like this, based on features in the
> D language.
> >
>
> Then what will be the behavior of:
>
> ```
> size_ = 13;
> ```
>
> If we consider this as "zombi" name, we could issue a warning like:
> "variable is deleted".
> But it will work fine in code like:
>
> ```
> void setSize(int i) require (StoreSize == true)
> {
> size_ = i;
> }
> void setSize(int) require (StoreSize == false)
> {
> // nothing
> }
> ```
>
> This will still be "viral" but at least we could easily reason about
> code as `size_` always means the same thing but
> in some cases is not accessible.
>

Yes, as discussed in
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3613.pdf#section.5
which is why I linked to it :-)