Example on mapping templated types that are not POD

test.jl

module OpenCV

using CxxWrap

struct Point{T}
    x::T
    y::T
end

@wrapmodule "build/lib/libtestlib.so"

function __init__()
    @initcxx
end

end

@show OpenCV.makepoint(1,2)
@show OpenCV.readpoint(OpenCV.Point(1,2))
@show OpenCV.readpointcref(OpenCV.Point(1,2))
@show OpenCV.readpoint(OpenCV.Point(1.0,2.0))
@show OpenCV.readpointcref(OpenCV.Point(1.0,2.0))

testlib.cpp

#include "jlcxx/jlcxx.hpp"

#include <opencv2/core/types.hpp>

template<typename T>
struct MyPoint
{
  T x;
  T y;
};

namespace jlcxx
{
  // Indicate that the type is not wrapped using add_type
  template<typename T> struct IsMirroredType<cv::Point_<T>> : std::true_type {};

  // Set the equivalent "C-compatible" type
  template<typename T> struct static_type_mapping<cv::Point_<T>> { using type = MyPoint<T>; };

  // This replaces the need to call map_type, useful for templated types
  template<typename T>
  struct julia_type_factory<cv::Point_<T>>
  {
    static inline jl_datatype_t* julia_type()
    {
      return (jl_datatype_t*)apply_type((jl_value_t*)jlcxx::julia_type("Point"), jl_svec1(julia_base_type<T>()));
    }
  };

  // Conversions need to be defined manually too:
  template<typename T>
  struct ConvertToJulia<cv::Point_<T>, NoMappingTrait>
  {
    MyPoint<T> operator()(const cv::Point_<T>& cpp_val) const
    {
      return *reinterpret_cast<const MyPoint<T>*>(&cpp_val);
    }
  };
  template<typename T>
  struct ConvertToCpp<cv::Point_<T>, NoMappingTrait>
  {
    inline cv::Point operator()(const MyPoint<T>& julia_val) const
    {
      return *reinterpret_cast<const cv::Point_<T>*>(&julia_val);
    }
  };
}

JLCXX_MODULE define_julia_module(jlcxx::Module& mod)
{
  mod.method("readpoint", [](cv::Point p) { return p.x + p.y; });
  mod.method("readpointcref", [](const cv::Point& p) { return p.x + p.y; });
  mod.method("readpoint", [](cv::Point2l p) { return p.x + p.y; });
  mod.method("readpointcref", [](const cv::Point2l& p) { return p.x + p.y; });
  mod.method("readpoint", [](cv::Point2d p) { return p.x + p.y; });
  mod.method("readpointcref", [](const cv::Point2d& p) { return p.x + p.y; });
  mod.method("makepoint", [](int x, int y) { return cv::Point{x,y}; });
}