Marco wrote:
Well, the last word is up to the author's library, however I'd be surprised if the following relations were not valid:
associativity: or_< T1, or_<T2, T3> > == or_< T1, T2, T3 > == or_< or_<T1, T2,>, T3 > and_< T1, and_<T2, T3> > == and_< T1, T2, T3 > == and_< and_<T1, T2,>, T3 >
commutativity: or_< T, U > == or_< U, T > and_< T, U > == and_< U, T >
absorption: or_< T, and_<T, U> > == T and_< T, or_<T, U> > == T
obviously where "==" means logical equivalence not C++ data type equality.
Yes, these relationships hold. My only considerations wrt the proposed extensions to proto::and_ and proto::or_ are: 1) Does it increase genericity? 2) Does it reduce bugs and/or increase discoverability in proto's interface? 3) Does it hurt compile times in the general case? Sounds like the answers to (1) and (2) are "Yes, somewhat." I'd need to measure to answer (3). -- Eric Niebler Boost Consulting www.boost-consulting.com