Re: [boost] boost::result_of and C++03

From: shunsuke (pstade.mb_at_[hidden])
Date: 2008-04-07 14:46:37

Eric Niebler wrote:
> What I'm saying is that, in C++03, polymorphic function objects are 
> broken, so we need the runtime equivalent of a metafunction class ... a 
> generator for monomorphic function objects. Call it a function class:
> 
> struct fun_class
> {
>    template<typename A>
>    struct apply
>    {
>      typedef ... result_type;
>      result_type operator()(
>          typedef add_const_ref<A>::type a
>      ) const
>      {
>        return ...;
>      }
>    };
> };
> 
> Now both the return type calculation *and* the operator() have access to 
> *all* the information about the arguments, even their lvalue/rvalue-ness.

After all, if you need "overload on rvalueness" in C++03,
some workaround is needed.

BTW, this doesn't need a new concept:
   foo(i, boost::rval(3));
I don't like it of course, though. :-)

Regards,

-- 
Shunsuke Sogame