On Dec 22, 2008, at 1:47 PM, Neal Becker wrote:
I'm interested in something like constrained, but applied to a vector of values. The case I'm interested in is a homogeneous vector of bounded int values, with bounds set at runtime.
It is trivial to have a vector<bounded<int> >, but this would not be space efficient in the case where the policies, bounds on all the values are the same.
Not as general, but possible right now: use bounded with the bounds as static members. This gives you as many classes of constraints as you care to spell out. Example follows. You're right though, a way to impart constraints from container to contained would be really cool. #include <iostream> #include <boost/constrained_value.hpp> #include <boost/mpl/assert.hpp> template<typename Tag, typename T> struct static_bound { operator T() const { return s_t; } static T s_t; }; struct Lower {}; struct Upper {}; template<> double static_bound<Lower, double>::s_t = -10.0; template<> double static_bound<Upper, double>::s_t = 10.0; int main(int argc, char *argv[]) { typedef boost::constrained_value::bounded<double, static_bound<Lower,double>, static_bound<Upper,double> >::type within_10; // there have been reports that this will fail on msvc? worx on gcc BOOST_MPL_ASSERT_RELATION( sizeof(within_10), ==, sizeof(double) ); within_10 x; x = 9; x = -7.5; try { x = 12; } catch(std::exception const& xep) { std::cout << "expect except: " << xep.what() << std::endl; } return 0; } Cheers, Gordon