namespace
boost
    {
    class
    exception
        {
        protected:
    
        exception();
        exception( exception const & x );    
        ~exception();    
        };
    }

Class boost::exception is designed to be used as a universal base for user-defined exception types.

An object of any type deriving from boost::exception can store data of arbitrary types, using the error_info wrapper and operator<<.

To retrieve data from a boost::exception object, use the get_error_info function template.