On Tue, Jul 1, 2008 at 8:32 PM, David Abrahams <dave@boostpro.com> wrote:
Giovanni Piero Deretta wrote:
I still do not see how can you 'fix' BOOST_TYPEOF to deduce const references correctly. Without that, you can't implement result_of with boost typeof.
As written elsewhere, treating a const rvalue as though it were a const lvalue should almost never cause a serious problem. It wouldn't be perfect, but it would work in a vast majority of cases.
Good point, it is possible to always deduce T& references correctly and collapase const T& to plain T. I was trying to come up with something a program that might break while working correctly with TR1 result_of, but the only thing that came to my mind is something like this, which is not a strong reason not to breaking compatibility: let 'first' be a result_of compatible function object that behaves like fusion::at_c<0>() typedef boost::tuple<int> tuple_t; tuple_t x(0); boost::result_of<filrst(tuple_t const&)>::type r = first(x); assert(&r == &boost::get<0>(x)); The assert will fail if result_of uses BOOST_TYPEOF. Just be safe, a result_of that uses typeof might have a different name. -- gpd