Re: [boost] typeof(int() + double())?

From: Howard Hinnant (hinnant_at_[hidden])
Date: 2002-03-08 10:56:35

On Friday, March 8, 2002, at 10:20  AM, Gabriel Dos Reis wrote:

> Howard Hinnant <hinnant_at_[hidden]> writes:
>
> | On Thursday, March 7, 2002, at 06:35  PM, rwgk wrote:
> |
> | > In the future, assuming that typeof is accepted into the standard,
> | > will I be able to do this ...
> | >
> | >   template<typename TypeLHS, typename TypeRHS>
> | >   struct binary_operator_traits {
> | >     typedef typeof(TypeLHS() + TypeRHS()) arithmetic;
> | >   };
> | >
> | > ... and avoid all the specializations?
> |
> | Hopefully yes.  You can do this with Metrowerks today, although by
> | default typeof is spelled __typeof__.  And it might be better to do 
> the
> | following to avoid requiring an accessible default constructor:
> |
> | template <class T> T make();
> |
> | template<typename TypeLHS, typename TypeRHS>
> | struct binary_operator_traits {
> |      typedef typeof(make<TypeLHS>() + make<TypeRHS>()) arithmetic;
>
> However, this would require a definition for make()...

Actually no.  typeof (at least ours) works like sizeof.  Expressions are 
not evaluated.  No definition of make() is required (or desired).

-Howard