...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::yap::if_else
// In header: <boost/yap/expression.hpp> template<typename Expr1, typename Expr2, typename Expr3> constexpr auto if_else(Expr1 && expr1, Expr2 && expr2, Expr3 && expr3);