In article <[EMAIL PROTECTED]>, Randall Hopper wrote:
> Thomas Heller:
> |> Python -> C++ -> Python Callback
> |>
> |> (example attached) an exception raised in the callback doesn't make it back
> |> across C++ to Python.
> ...
> |> void callback_wrapper( void *user_data )
> |> {
> |> // Acquire interpreter lock
> |> PyGILState_STATE gstate = PyGILState_Ensure();
> |> ...
> |> // Call Python
> |> pyresult = PyEval_CallObject( pyfunc, pyargs );
> |> ...
> |
> | if (pyresult == NULL)
> | PyErr_Print();
> |
> |> // Free interpreter lock
> |> PyGILState_Release(gstate);
> |> }
> |
> |PyErr_Print() will do the 'right' thing?s.
>
> Thanks for the reply. However, this won't:
>
> a) Stop the main Python script, and
> b) Print the full stack trace (including Python and C++ SWIG wrapper)
>
> Is there a clean way to save the full exception state in the callback
> before the PyGILState_Release(), and restore it when we return across the
> C++ wrapper?
>
> If I knew what the proper "save" and "restore" exception state code bits
> were, I could easily implement this with exception typemaps in SWIG.
>
> Thanks,
>
> Randall
>
> P.S. Perhaps PyGILState_Release should take an argument instructing it to
> exclude exception state when resetting the interpreter state back to its
> original state.
Randall:
It's not the job of the PyGILState_* functions to manage exception details for
you.
I always solved this problem a different way, by saving the exception in an
instance variable
within the Python callback, and using a condition variable so that the main
thread could abort on a callback's
failure. Notably, our callsbacks are always invoked from a C++ thread that the
main Python interepreter didn't
create, and our main Python intepreter is blocked on a mutex most of the time.
I saved the exception state by retrieveing it from sys.exc_info(), which
contains all the traceback object data as Python variable.
I think you can get the same info from your C++ callback wrapper, and use
PyErr_Fetch and PyErr_Restore to save and restore the
exception sate.
Dave
--
http://mail.python.org/mailman/listinfo/python-list
