Boost Exception

Cloning and Re-throwing an Exception

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

#include <boost/exception_ptr.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(
    ... )
        {
        error = boost::current_exception();
        }
    }

In the above example, note that current_exception() captures the original type of the exception object. The exception 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);
    }

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

if there is not enough memory, in which case the returned exception_ptr points to an instance of std::bad_alloc, or
if enable_current_exception() was not used in the throw-expression passed to the original throw statement and the current implementation does not have the necessary compiler-specific support to copy the exception automatically, in which case the returned exception_ptr points to an instance of unknown_exception.

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

Boost Exception

Cloning and Re-throwing an Exception

See also: