On Jul 22, 2004, at 8:08 AM, Arkadiy Vertleyb wrote:
Giovanni Bajo wrote:
Arkadiy Vertleyb wrote:
One more addition to the typeof library is a macro, that, unlike BOOST_TYPEOF(), which removes top-level consts and references, attempts to be closer to the decltype, by preserving lvalue-ness of its argument:
BOOST_TYPEOF_PRESERVE_LVALUE(expr)
I do admit that the name is quite clumzy :(
BOOST_DECLTYPE?
Well, unfortunately, it's not exactly decltype :(
In particular:
int i; const int ci = 0;
decltype BOOST_TYPEOF_PRESERVE_LVALUE -------- ---------------------------- i int int& ci const int const int&
etc.
It is calculated by binding a T& to the expression. If it can't be bound the type is the same as one returned by BOOST_TYPEOF. If it can, it's either reference or const reference, depending on the constness of T.
First of all, this is really cool. My initial reaction to the typeof lib was "cool, we have typeof" but "darn, I can't use it for result_of". Whatever we name this macro, it's directly usable for result_of. That's great! As for naming: It could just be called BOOST_DECLTYPE, with the caveat that it doesn't act quite perfectly for variables. Frankly, I couldn't care much less about variables: you rarely need the type of those, although I could easily contrive cases. BOOST_LVALUE_TYPEOF might be the most obvious name: it returns a reference if it gets an lvalue, a non-reference otherwise. Doug