The code like
```
if (vect) foo(vect[0]);
```
doesn't make sense for all containers, e.g. for unordered_map so this
`operator bool` proposal is not generic.

My personal mental model about `operator bool` is a check when an object
doesn't exist or it's not usable (in a normal way) or, if it's a wrapper,
it wraps nothing.

On Thu, Oct 19, 2023 at 1:40 PM Marcin Jaczewski via Std-Proposals <
std-proposals_at_[hidden]> wrote:

> czw., 19 paź 2023 o 12:27 Bo Persson via Std-Proposals
> <std-proposals_at_[hidden]> napisał(a):
> >
> > On 2023-10-19 at 12:05, Alex Rozenman via Std-Proposals wrote:
> > > In many cases, when it is needed to check if a container not empty,
> > > "size()" or "empty()" functions are used:
> > >
> > > if (vect.size() != 0) {
> > >
> > > // vector is not empty
> > >
> > > }
> > >
> > > if (!vect.empty()) {
> > >
> > > // vector is not empty
> > >
> > > }
> > >
> > >
> > > It seems that both variants are not expressive enough, so an explicit
> > > function may be required, like:
> > >
> > > if (vect.not_empty()) {
> > >
> > > // vector is not empty
> > >
> > > }
> > >
> >
> > Could you live with if(not vect.empty()) ?
> >
> > If so, that already works.
> >
> >
> >
> > >
> > > In this message I would like to suggest to use of a bool casting
> > > operator as the most clean form of this function:
> > >
> > > if (vect) {
> > >
> > > // vector is not empty
> > >
> > > }
> > >
> >
> > It might be "clean", but I read this as vect is a pointer that might be
> > null. Not obvious how this is an improvement.
>
> ```
> if (vect) foo(vect[0]);
> if (ptr) foo(ptr[0]);
> ```
> Both are equivalent.
> At least in my code base I use the `bool` operator like this.
>
> >
> >
> >
> >
> > --
> > Std-Proposals mailing list
> > Std-Proposals_at_[hidden]
> > https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
> --
> Std-Proposals mailing list
> Std-Proposals_at_[hidden]
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>

-- 
Regards,
Oleksandr Koval.