On 7/6/06, Emil Dotchevski <emildotchevski@hotmail.com> wrote:
template <class T> exception_info * get_exception_info( T & );
It can be used in a catch( T & ) block, to check if the exception object has a sub-object of class exception_info.
Why return a pointer? How about considering the use of a reference instead? Perhaps: template < typename T > exception_info & get_exception_info ( T & ); That way, the return can only be accessed using an exception_info reference. Consider this example (which is considerably cleaner to read, IMO) : try { throw failed<read_error>() << wrap_string<tag_file_name>("example.txt"); } catch (read_error & e) { exception_info info = get_exception_info(e); if (info) { // deal with the info... } // deal with the exception... }; This also avoids the possibility of mis-use of pointers, because client code can still do a cast of the pointer to refer to something else -- which although it is hackish, is something you'd want to avoid. It also makes the following possible: std::cout << get_string<tag_file_name>(get_exception_info(e)) << std::endl; Which is a little long for my taste, but readable nonetheless. HTH -- Dean Michael C. Berris C/C++ Software Architect Orange and Bronze Software Labs http://3w-agility.blogspot.com/ http://cplusplus-soup.blogspot.com/ Mobile: +639287291459 Email: dean [at] orangeandbronze [dot] com