"Thorsten Ottosen" wrote
Andy Little wrote:
I dont understand the char_type member typedef of the traits class. The functions that use it all seeem to be free functions which could change from e.g
template<class Ptree> void read_xml(std::basic_istream<typename Ptree::char_type> &stream, Ptree &pt, int flags = 0);
to
template<class Ptree, class Char> void read_xml(std::basic_istream<Char> &stream, Ptree &pt,int flags = 0);
without problems. That would remove one level of coupling wouldnt it?
I'm not sure it is worth speculating too much about coupling. The function will implicitly depend on the interface of basic_ptree<> anyway. So there is no reason to hide that fact.
The only resaon for the char_type traits parameter is for stream I/O though isnt it? IOW because of this coupling each ptree type can only be serialised to a stream parameterised on one char type. You cannot therefore have a wide string ptree loaded from a char file for example.
I consider this interface most elegant (because ADL also works):
namespace boost { template< class Traits > void read_xml( std::basic_istream<typename Traits::char_type>& str, basic_ptree<Traits>& tree, int flags = 0 ); }
ADL also works ... namespace boost { template< class Traits , typename Char> void read_xml( std::basic_istream<Char>& str, basic_ptree<Traits>& tree, int flags = 0 ); } regards Andy Little