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copied!<p>Make your bool_xxx functions actually functors of a specific kind of type (tag dispatching would be enough). Then override || and && for them such that these operators return a bool_and, or bool_or. Then you can use your bool_ predicates like so:</p> <pre><code> std::find_if(vect.begin(), vect.end(), bool_x1() || bool_x2() && (bool_x3() || bool_x4() && bool_x5())); </code></pre> <p>If you're tempted to write a "where" function then you apparently want to do this more than once with a different set of bool_xxx functions. Even if you know that you want a certain type of composition now, you may as well make it as universal as possible. This is how I'd do it.</p> <p>Edit:</p> <p>Based on this comment: <i>@Jerry: For example I need to know: id=where(v < 10.0 && v>1.0); and somewhere later I would like to know: id=where(v < fun(v));</i> you may be better off with boost::lambda:</p> <pre><code> namespace l = boost::lambda; std::find_if(vect.begin(), vect.end(), l::_1 < 10.0 && l::_1 > 1.0); std::find_if(vect.begin(), vect.end(), l::_1 < l::bind(fun, l::_1)); </code></pre> <p>Or, if you hate lambda or aren't allowed to use it...or just want a very slightly nicer syntax (but inability to use functions directly) then just make your own placeholder type and override it to return bool_xxx functors on operators <, >, etc...</p> <p>Edit2: Here's an untested where that returns a vector of iterators to all objects matching:</p> <pre><code> template < typename ForwardIter, typename Predicate > std::vector<ForwardIter> where(ForwardIter beg, ForwardIter end, Predicate pred) { ForwardIter fit = std::find_if(beg,end,pred); if (fit == end) return std::vector<ForwardIter>(); ForwardIter nit = fit; ++nit; std::vector<ForwardIter> collection = where(nit,end,pred); collection.push_front(fit); return collection; } </code></pre> <p>It's recursive and could be slow on some implementations but there's one way to do it.</p>

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