[C++-sig] bad exception conversion
Wichert Akkerman
wichert at wiggy.net
Thu Jun 14 11:19:32 CEST 2012
Hi Jim,
On 06/14/2012 01:02 AM, Jim Bosch wrote:
> I suspect the problem is that your custom exception doesn't derived
> from Python's built-in Exception base class. Unfortunately, it's
> impossible to do that with a Boost.Python wrapped class, but you can
> get it all done with the Python C API:
>
> namespace {
> PyObject *UnsuitableErrorType = NULL;
>
> void translator(const unsuitable_error &e) {
> std::list<const char*>::const_iterator i;
> PyObject* unicode;
> boost::python::list reasons;
> for (i=e.reasons.begin(); i!=e.reasons.end(); i++) {
> boost::python::handle<> unicode(PyUnicode_FromString(*i));
> reasons.append(boost::python::object(unicode));
> }
For some odd reason that append line fails with this error:
/usr/include/boost/python/converter/arg_to_python.hpp:194:7:
instantiated from 'void
boost::python::converter::detail::reject_raw_object_ptr(T*) [with T =
_object]'
/usr/include/boost/python/converter/arg_to_python.hpp:217:7:
instantiated from
'boost::python::converter::detail::pointer_deep_arg_to_python<Ptr>::pointer_deep_arg_to_python(Ptr)
[with Ptr = _object*]'
/usr/include/boost/python/converter/arg_to_python.hpp:256:13:
instantiated from
'boost::python::converter::arg_to_python<T>::arg_to_python(const T&)
[with T = _object*]'
/usr/include/boost/python/object_core.hpp:393:69: instantiated from
'static PyObject* boost::python::api::object_initializer_impl<is_proxy,
is_object_manager>::get(const T&, mpl_::false_) [with T = _object*, bool
is_proxy = false, bool is_object_manager = false, PyObject = _object,
mpl_::false_ = mpl_::bool_<false>]'
/usr/include/boost/python/object_core.hpp:315:7: instantiated from
'PyObject* boost::python::api::object_base_initializer(const T&) [with T
= _object*, PyObject = _object]'
/usr/include/boost/python/object_core.hpp:334:49: instantiated from
'boost::python::api::object::object(const T&) [with T = _object*]'
../../python/article.cc:23:48: instantiated from here
/usr/include/boost/python/converter/arg_to_python.hpp:181:11: error:
incomplete type
'boost::python::converter::detail::cannot_convert_raw_PyObject<_object*>' used
in nested name specifier
which is odd some it is essentially the same code as before, only with
the reasons list moved out of a class into the local scope.
> boost::python::handle<> error(
> PyObject_CallFunctionObjArgs(
> UnsuitableErrorType, NULL
> )
> );
> PyObject_SetAttrString(error.get(), "reasons", reasons.get());
Small typo: reasons.ptr() there since reasons is an object, not a handle.
> I haven't tested any of that, but hopefully it's close enough to point
> you in the right direction.
That's very helpful, thanks.
Wichert.
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