Re: [Boost-users] [bind, tuple] Custom comparison of tuple elements

Hi Mark, On 1/11/07, Mark Ruzon wrote:

Assume we have a range of objects of type tuple and a function object that compares two objects of type T1. How would a person sort this range using this function object and bind? I want something along the lines of:

std::sort(first, last, boost::bind<bool>(comp, boost::bind(boost::get<0>, _1), boost::bind(boost::get<0>, _2)));

as Peter pointed out using overloaded function templates are a pain. However, if you define this one little get function (not even a functor) you may use it with bind easily: template< int N, class Tup > inline typename boost::tuples::element::type& get(Tup& t) { return boost::tuples::get<N>(t); } Then, inside some scope where you can access this and bind arguments to your custom comparison functor typedef boost::tuples::tuple tup; std::vector< tup > a(5); namespace b = boost; std::sort( a.begin(), a.end(), b::bind( mycompare, b::bind(get<0,tup>, ::_1), b::bind(get<0,tup>, ::_2) ) ); Now that you want to play around with these "beauties" (bind, tuple, etc..), here http://rafb.net/p/q8aeR482.html is a piece of compiling (and working) code which you might find entertaining. It also uses Boost.Lambdato fill-up the tuple vector, print-it out and sort with an inline lambda expression in addition to boost::bind'ed externally crafted functor. hth - levent -- Server Levent Yilmaz Mechanical Engineering @ PITT