Not sure I got this. Any container may be empty or not empty. 

On Thu, Oct 19, 2023 at 1:47 PM Oleksandr Koval via Std-Proposals <std-proposals@lists.isocpp.org> wrote:

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@lists.isocpp.org> wrote:

czw., 19 paź 2023 o 12:27 Bo Persson via Std-Proposals
<std-proposals@lists.isocpp.org> 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@lists.isocpp.org
> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
--
Std-Proposals mailing list
Std-Proposals@lists.isocpp.org
https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals

--

Regards,

Oleksandr Koval.

--
Std-Proposals mailing list
Std-Proposals@lists.isocpp.org
https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals

--

Best regards,
Alex Rozenman (rozenman@gmail.com).