[C++-sig] bad exception conversion

[Wichert Akkerman]

On 06/14/2012 11:19 AM, Wichert Akkerman wrote:
> 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.

Stupid copy & paste error on my side - I forgot the handle bit :(

Regards,
Wichert.