[Python] Swig: C++ / Python director and std::vector<double>

I try to wrap a c++ code in python with swig. I use the director instruction to overload few methods of a virtual class but I have some issues with the methods that should return tabulated data: std::vector or Eigen::Vector.

Let's say we have a c++ class

class myCppClass
{
public:
myCppClass(){}
virtual std::vector<double> compute_things();
};


The .i file that wrap this class looks like:

%module(package="example", directors="1", allprotected="1", "threads"=1) My_Example

%{
#include <MyCppClass.h>
}

%import <typemaps.i>
%include <std_vector.i>
%include <eigen.i>
%import "numpy.i"

%feature("director") myCppClass;

%include <MyCppClass.h>


Then in python

class myPythonClass(myCppClass):

def __init__(self):
super().__init__()

def compute_things(self):
return np.array([2.0, 1.0])


myclass = myPythonClass()
myclass.compute_things()



Once everything is compiled, the class creation goes well but the compute_things() method crash without any clue about the error. If I return an int or a double everything goes well. I put few error handling instruction in the .i file but none them are activated.

%feature("director:except") {
if ($error != NULL) {
PyErr_Print();
if (PyErr_GivenExceptionMatches($error, PyExc_TypeError)) {
throw std::invalid_argument("director:except TypeError");
}
else {
throw Swig:irectorMethodException("Unknown exception thrown by Python SWIG director method");
}
}
}

%exception{
try { $action }
catch (std::invalid_argument& exc) {
if (std::string(exc.what()) == "director:except TypeError") {
SWIG_exception_fail(SWIG_TypeError, "TypeError exception thrown by Python SWIG director method");
}
else {
std::string message = std::string("Exception '") + std::string(exc.what()) + "' thrown by C++ function : $fulldecl";
SWIG_exception_fail(SWIG_ValueError, message.c_str());
}
}
catch (Swig:irectorMethodException& exc) {
SWIG_exception_fail(SWIG_UnknownError, exc.what());
}
catch (Swig:irectorException &e) { SWIG_fail; }
catch (...) {
SWIG_exception_fail(SWIG_UnknownError, "Unknown exception thrown by C++ function : $fulldecl");
}
}

%include "exception.i"
%exception
{
try
{
$action
}
catch (const std::runtime_error& e) {
SWIG_exception(SWIG_RuntimeError, e.what());
}
catch (const std::invalid_argument& e) {
SWIG_exception(SWIG_ValueError, e.what());
}
catch (const std:ut_of_range& e) {
SWIG_exception(SWIG_IndexError, e.what());
}
catch (...) {
SWIG_exception(SWIG_RuntimeError, "unknown exception");
}
}


Does I reached a limitation of Swig or there is something I am missing ?

Thanks a lot for your help.

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