Boost Exception

Cloning and Re-throwing an Exception

When you catch a boost::exception, you can call clone_exception() to get an exception_ptr object:

#include <boost/exception/cloning.hpp>
#include <boost/thread.hpp>
#include <boost/bind.hpp>

void do_work(); //throws cloning-enabled boost::exceptions

void
worker_thread( boost::exception_ptr & error )
    {
    try
        {
        do_work();
        error = boost::exception_ptr();
        }
    catch(
    boost::exception & e )
        {
        error = boost::clone_exception(e);
        }
    }

In the above example, note that clone_exception() captures the original type of the exception object, even though e refers to the base type boost::exception. This original type can be thrown again using the rethrow_exception() function:

// ...continued

void
work()
    {
    boost::exception_ptr error;
    boost::thread t( boost::bind(worker_thread,boost::ref(error)) );
    t.join();
    if( error )
        boost::rethrow_exception(error);
    }

Clone_exception() could fail to copy the original exception object in the following cases:

Regardless, the use of clone_exception() and rethrow_exception() in the above examples is well-formed.