Thorsten Ottosen wrote:
"Neal Becker" <ndbecker2@verizon.net> wrote in message news:chvoo4$qbl$1@sea.gmane.org... | It is not unusual to need to construct a container from another where | one or the other doesn't comply with sequence. | | When generic code needs to convert to a container of unknown type (e.g., | the return container type of a function is a template parameter), a | generic | constructor is useful, and could be part of range. Here is the idea: | | #ifndef const_from_range_hpp | #define const_from_range_hpp | | #include <boost/range.hpp> | #include <algorithm> | #include <boost/numeric/ublas/vector.hpp> | | namespace detail { | template<typename cont_t, typename range> | struct construct_from_range_impl { | cont_t operator() (range const& r) { | return cont_t (boost::begin (r), boost::end (r)); | } | };
Please see the "Utility" section of the docs. You would be looking for copy_range().
| template<typename T, typename range> | struct construct_from_range_impl<boost::numeric::ublas::vector<T>, | range> | { | typedef typename boost::numeric::ublas::vector<T> ret_t; | ret_t operator() (range const& r) { | ret_t v (boost::size (r)); | std::copy (boost::begin (r), boost::end (r), v.begin());
this can write past the end
| return v; | } | }; | }
hm..if ublas support is needed one could either do
1. give ublas classes a constructor that takes two iterators 2. overload copy_range
I would prefer 1.
How would 2 work? copy_range is a function, so can't have a partial specialization. How would you overload for converting an arbitrary range to ublas::vector<T>?