[Boost-users] [fusion][Functional] LValue arguments limitation

Fusion manual says: Only LValue arguments are accepted. To overcome this limitation, apply Boost.Functional/Forward. I understand that this has to do with not being able to pass literal constants to the function, e.g. unfused<f> uf; uf(1., 2.); //can't First: 1) can anybody explain why is this? 2) uf( (double const&) 1., (double const&) 2. ); seems to work, but it is probably a hack. (not portable maybe?) 3) the manual says also to use Boost.Functional/Forward to overcome this limitation. What does it mean by this? Thank you, Alfredo