Dean Michael Berris wrote:
On 7/5/06, Peter Dimov <pdimov@mmltd.net> wrote:
But the whole point is that in some scenarios you want to catch T, not exception_info. You are interested in a read_error and have an appropriate response to it ready, but the rest of the exceptions must be propagated unharmed.
So you catch( read_error const & r ) and use dynamic_cast to see whether it also contains exception_info.
Now I get it.
Is there any other way of doing it than dynamic_cast'ing the exception then?
You need the dynamic_cast, because all you have is a read_error pointer, and you need an exception_info pointer *if* it is available. For one reason or another, the program could throw a "naked" read_error object (as opposed to using throw failed<read_error>()) and in this case you will not have an exception_info sub-object in the exception. The reason why I have not hidden the dynamic_cast in a function get_exception_info() is that the only implementation possible is through a dynamic_cast, so why bother. --Emil