Re: [boost] Re: safe_bool alternative?

From: Douglas Paul Gregor (gregod_at_[hidden])
Date: 2003-11-28 11:07:50

On Fri, 28 Nov 2003, David Abrahams wrote:

> Daniel Wallin <dalwan01_at_[hidden]> writes:
>
> >> Personally, I like Joel de Guzman's version, but I also like using
> >> boost
> >> operators, so for me a mix of the two would be good:
> >> [snip]
> >
> > Here's another one:
> >
> > template <class T>
> > struct bool_testable
> > {
> > protected:
> >      bool_testable()
> >      {
> >          BOOST_STATIC_ASSERT(!(
> >              boost::is_convertible<T, int>::value)
> >          );
> >      }
>
> Anything based on this technique will unfortunately fail when T has a
> private conversion to int.

So will any attempts to use that type in a boolean context, because the
int overload will be selected. If you need a conversion to int, you can't
use bool_testable.

        Doug