Tzu-Chien Chiu wrote:
Any boost library can make me write the expression like
int x = 3; if ( x in list(3, 5, 6, 7) ) { ... }
I don't know about the boost libraries, but I quickly sketched out something you might be interested in, based on something I saw on one of the news groups. All you have to do is to write a binary predicate functor with bool operator()(int,<whatever your list type is>). It's untested, but a quick syntax check with g++ 3.4.2 works fine. Usage will be if (x <in> list(3,5,6,7) ) { ... } I hope that's more or less what you're after; I don't know if you want that list type/function as well. The code itself is attached. Be sure to fix the template parameter in the unnamed namespace.. David Hall template <class F> struct operator_t { operator_t(F f=F()): f(f) {} F f; }; // Make a binary predicate functor that takes two arguments that iterates over your list... namespace { operator_t<YOU FILL IN HERE> in; } namespace detail { template <class T, class F> struct operator_t_bind { operator_t_bind(const T & x,F & f):lhs(x),f(f) {} const T & lhs; const F & f; }; } template <class T,class F> detail::operator_t_bind<T,F> operator<(const T & lhs,operator_t<F> & op) { return detail::operator_t_bind<T,F>(lhs,op.f); } template <class T, class F,class RHS> bool operator>(const detail::operator_t_bind<T,F> & binder,const RHS & rhs) { return binder.f(binder.lhs,rhs); }