throw_exception
#include <boost/throw_exception.hpp>
namespace
boost
    {
#ifdef BOOST_NO_EXCEPTIONS
    void throw_exception( std::exception const & e ); // user defined
#else
    template <class E>
    void throw_exception( E const & e );
#endif
    }
Effects:
-  If BOOST_NO_EXCEPTIONS is not defined, boost::throw_exception(e) throws an exception of unspecified type that derives publicly from E and from boost::exception.
-  If BOOST_NO_EXCEPTIONS is defined, the function is left undefined, and the user is expected to supply an appropriate definition. Callers of throw_exception are allowed to assume that the function never returns; therefore, if the user-defined throw_exception returns, the behavior is undefined.
Requirements:
E must derive publicly from std::exception. E may or may not derive from boost::exception.
Notes:
-  The emitted exception can be intercepted as E &, std::exception &, or boost::exception &.
-  The emitted exception supports boost::exception_ptr.
-  If BOOST_EXCEPTION_DISABLE is defined and BOOST_NO_EXCEPTIONS is not defined, boost::throw_exception(e) equivalent to throw e.