On 7/7/06, Dean Michael Berris <mikhailberis@gmail.com> wrote:
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:
I prefer the pointer, that way one can define the variable inside the if if(exception_info* p = get_exception_info(e)) { }
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... };
IMO, the pointer is cleaner.
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:
casts can be done with references just a-like.
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
-- Felipe Magno de Almeida