[boost] Re: Re: Quick Question...

From: Andrei Alexandrescu (andrewalex_at_[hidden])
Date: 2002-04-23 09:56:55

"David Abrahams" <david.abrahams_at_[hidden]> wrote in message
news:0ef801c1eac7$0af69c10$6501a8c0_at_boostconsulting.com...
> From: "Paul Mensonides" <pmenso57_at_[hidden]>
> > template<class T> class has_key_nested {
> >     private:
> >         template<class U> static small_t check(typename
U::nested*);
> >         template<class U> static large_t check(...);
> >     public:
> >         static const bool value = sizeof(check<T>(0)) ==
> sizeof(small_t);
> > };
> >
> > Now that I look at it, 14.8.2/2 bullet 3, sub-bullet 3 appears to
say
> it is
> > legal, but I don't speak fluent ISO. :)
>
> Paul,
>
> It's legal, and I already used your trick to implement an is_class
which
> works on incomplete and noncopyable types with a conforming compiler
> (see the CVS).

This is a much simpler idiom than what I saw on clcm. That's great,
because it can have tons of cool applications.

Who invented it?

Andrei