Ranges adaptors *do* provide (explicit) operator bool since they all
derived from ‘view_interface’.

Olaf van der Spek via Std-Proposals <std-proposals_at_[hidden]>於
2023年11月1日 週三，04:44寫道：

> On Thu, Oct 19, 2023 at 12:06 PM Alex Rozenman via Std-Proposals
> <std-proposals_at_[hidden]> wrote:
> > In this message I would like to suggest to use of a bool casting
> operator as the most clean form of this function:
>
> Nice suggestion. ;)
>
> https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3509.htm
>
>
> --
> Olaf
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