Error by wrapping c++ class with pybind11 using carma (armadillo matrices and numpy arrays)

Question

I have a simple example of trying to use carma and pybind11 to go to and from armadillo matrices and numpy arrays based off of this example . Without the printarma() function, the code works ie with just wrapping using pybind11 the code compiles and I can run it in python. The problem here seems to be with carma. Here is the code:

#include <ostream>
#include <iostream>
#include <armadillo>
#include <carma/carma.h>
#include <pybind11/pybind11.h>
#include <pybind11/numpy.h>

namespace py = pybind11;

using namespace std;

class Base
{
public:
    virtual void test() = 0;
    virtual void printarma() = 0;
};
class Derived: public Base
{

public:
    void printarma(py::array_t<double> & arr) {arma::Mat<double> mat = carma::arr_to_mat<double>(arr);
            std::cout << mat<< std::endl;}
    void test() {cout << "Test";}
};


PYBIND11_MODULE(example,m) {
    py::class_<Base>(m, "Base");

    py::class_<Derived, Base>(m, "Derived")
        .def(py::init<>())
        .def("test", &Derived::test);
        m.def("printarma", &Derived::printarma,py::arg("arr"));
} 

I run the command:

c++ -O3 -Wall -shared -std=c++14 -fPIC -larmadillo `python3 -m pybind11 --includes` abstrakt_test.cpp -o example`python3-config --extension-suffix`

And the errors are:

In file included from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:47,
                 from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/numpy.h:12,
                 from /usr/local/include/carma/carma/converters.h:24,
                 from /usr/local/include/carma/carma/arraystore.h:1,
                 from /usr/local/include/carma/carma.h:1,
                 from abstrakt_test.cpp:18:
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/detail/init.h: In instantiation of ‘Class* pybind11::detail::initimpl::construct_or_initialize(Args&& ...) [with Class = Derived; Args = {}; typename std::enable_if<(! std::is_constructible<_Tp, _Args>::value), int>::type <anonymous> = 0]’:
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/detail/init.h:174:66:   required from ‘static void pybind11::detail::initimpl::constructor<Args>::execute(Class&, const Extra& ...) [with Class = pybind11::class_<Derived, Base>; Extra = {}; typename std::enable_if<(! Class::has_alias), int>::type <anonymous> = 0; Args = {}]’
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:1148:9:   required from ‘pybind11::class_<type_, options>& pybind11::class_<type_, options>::def(const pybind11::detail::initimpl::constructor<Args ...>&, const Extra& ...) [with Args = {}; Extra = {}; type_ = Derived; options = {Base}]’
abstrakt_test.cpp:45:26:   required from here
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/detail/init.h:63:64: error: invalid new-expression of abstract class type ‘Derived’
 inline Class *construct_or_initialize(Args &&...args) { return new Class{std::forward<Args>(args)...}; }
                                                                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
abstrakt_test.cpp:31:7: note:   because the following virtual functions are pure within ‘Derived’:
 class Derived: public Base
       ^~~~~~~
abstrakt_test.cpp:29:18: note:  ‘virtual void Base::printarma()’
     virtual void printarma() = 0;
                  ^~~~~~~~~
In file included from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/numpy.h:12,
                 from /usr/local/include/carma/carma/converters.h:24,
                 from /usr/local/include/carma/carma/arraystore.h:1,
                 from /usr/local/include/carma/carma.h:1,
                 from abstrakt_test.cpp:18:
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h: In instantiation of ‘void pybind11::cpp_function::initialize(Func&&, Return (*)(Args ...), const Extra& ...) [with Func = pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...), const Extra& ...) [with Return = void; Class = Derived; Arg = {pybind11::array_t<double, 16>&}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, pybind11::arg}]::<lambda(Derived*, pybind11::array_t<double>&)>; Return = void; Args = {Derived*, pybind11::array_t<double, 16>&}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, pybind11::arg}]’:
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:78:9:   required from ‘pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...), const Extra& ...) [with Return = void; Class = Derived; Arg = {pybind11::array_t<double, 16>&}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, pybind11::arg}]’
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:819:22:   required from ‘pybind11::module& pybind11::module::def(const char*, Func&&, const Extra& ...) [with Func = void (Derived::*)(pybind11::array_t<double>&); Extra = {pybind11::arg}]’
abstrakt_test.cpp:47:55:   required from here
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:133:50: error: static assertion failed: The number of argument annotations does not match the number of function arguments
         static_assert(expected_num_args<Extra...>(sizeof...(Args), cast_in::has_args, cast_in::has_kwargs),
                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/attr.h:13,
                 from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/pybind11.h:44,
                 from /home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/numpy.h:12,
                 from /usr/local/include/carma/carma/converters.h:24,
                 from /usr/local/include/carma/carma/arraystore.h:1,
                 from /usr/local/include/carma/carma.h:1,
                 from abstrakt_test.cpp:18:
/home/mikanim/anaconda3/envs/pybind/lib/python3.7/site-packages/pybind11/include/pybind11/cast.h:1958:57: error: ‘std::enable_if_t<std::is_void<_Res>::value, pybind11::detail::void_type> pybind11::detail::argument_loader<Args>::call(Func&&) && [with Return = void; Guard = pybind11::detail::void_type; Func = pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...), const Extra& ...) [with Return = void; Class = Derived; Arg = {pybind11::array_t<double, 16>&}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, pybind11::arg}]::<lambda(Derived*, pybind11::array_t<double>&)>&; Args = {Derived*, pybind11::array_t<double, 16>&}; std::enable_if_t<std::is_void<_Res>::value, pybind11::detail::void_type> = pybind11::detail::void_type]’, declared using local type ‘pybind11::cpp_function::cpp_function(Return (Class::*)(Arg ...), const Extra& ...) [with Return = void; Class = Derived; Arg = {pybind11::array_t<double, 16>&}; Extra = {pybind11::name, pybind11::scope, pybind11::sibling, pybind11::arg}]::<lambda(Derived*, pybind11::array_t<double>&)>’, is used but never defined [-fpermissive]
     enable_if_t<std::is_void<Return>::value, void_type> call(Func &&f) && {

Thanks in advance!

EDIT:

Code without carma:

c++ -O3 -Wall -shared -std=c++11 -fPIC `python3 -m pybind11 --includes` abstrakt_test.cpp -o example`python3-config --extension-suffix`



#include <ostream>
#include <iostream>
#include <pybind11/pybind11.h>


namespace py = pybind11;
using namespace std;

class Base
{
public:
    virtual void test() = 0;
};
class Derived: public Base
{

public:

    void test() {cout << "Test";}
};

PYBIND11_MODULE(example,m) {
    py::class_<Base>(m, "Base");

    py::class_<Derived, Base>(m, "Derived")
        .def(py::init<>())
        .def("test", &Derived::test);
} 

Answer 1

At the end it was two things: the virtual function in the Base class needed to add py::array_t<double> & arr to it and the semicolon at the end at .def needed to be deleted along with the m before .def . This code compiles and works in python:

class Base
{
public:
    virtual void test() = 0;
    virtual void printarma(py::array_t<double> & arr) = 0;
};
class Derived: public Base
{

public:
    void printarma(py::array_t<double> & arr) {arma::Mat<double> mat = carma::arr_to_mat<double>(arr);
            std::cout << mat<< std::endl;}
    void test()  {cout << "Test";}
};


PYBIND11_MODULE(example,m) {
    py::class_<Base>(m, "Base");

    py::class_<Derived, Base>(m, "Derived")
        .def(py::init<>())
        .def("test", &Derived::test)
        .def("printarma", &Derived::printarma,py::arg("arr"));