From: David Abrahams (david.abrahams_at_[hidden])
Date: 2002-01-23 13:05:18
Ah good, that avoids using inheritance to distinguish these babies...
but is char really guaranteed to be smaller than double (half-joking only).
-Dave
----- Original Message -----
From: "Douglas Gregor" <gregod_at_[hidden]>
> I use the same thing in Boost.Function. From
boost/function/function_base.hpp
>
> // Determine if the incoming argument is a reference_wrapper
> #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
> template<typename T>
> struct is_ref
> {
> BOOST_STATIC_CONSTANT(bool, value = false);
> };
>
> template<typename T>
> struct is_ref<reference_wrapper<T> >
> {
> BOOST_STATIC_CONSTANT(bool, value = true);
> };
> #else // no partial specialization
> typedef char yes_type;
> typedef double no_type;
>
> no_type is_ref_tester(...);
>
> template<typename T>
> yes_type is_ref_tester(reference_wrapper<T>*);
>
> template<typename T>
> struct is_ref
> {
> static T* t;
> BOOST_STATIC_CONSTANT(bool,
> value = (sizeof(is_ref_tester(t)) == sizeof(yes_type)));
> };
> #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
>
> I'd be glad to have any form of this code in ref.hpp, and get it out of
> detail::function.
>
> Doug