Rcpp错误：静态断言失败：无法将类型转换为SEXP，为什么？

Question

错误

我不明白为什么我使用Rcpp（版本1.0.2）时出现此编译错误：

来自文件/home/rmagno/R/x86_64-pc-linux-gnu-library/3.6/Rcpp/include/Rcpp/internal/wrap.h：

Line 523 static assertion failed: cannot convert type to SEXP

错误源

我正在尝试从GLFW库包装此C函数glfwSetKeyCallback。

而且我知道该错误源于下面的CPP源文件，但我不明白我在做什么错：

glfw_types.h

#ifndef RCPP_GLFW_TYPES_H
#define RCPP_GLFW_TYPES_H

#include <Rcpp.h>
#include <GLFW/glfw3.h>

// https://stackoverflow.com/questions/41210595/s4-object-with-a-pointer-to-a-c-struct

typedef Rcpp::XPtr<GLFWwindow, Rcpp::PreserveStorage, glfwDestroyWindow> GLFWwindow_ptr;

#endif

glfw_set_key_callback.cpp

#include "glfw_types.h"
using namespace Rcpp;

namespace {
  std::unique_ptr<Rcpp::Function> key_callback_func_ptr;
}

void glfw_set_key_callback_wrapper(GLFWwindow* window, int key, int scancode, int action, int modes)
{
  (*key_callback_func_ptr)(window, key, scancode, action, modes);
}

// [[Rcpp::export]]
void glfw_set_key_callback(GLFWwindow_ptr window, Rcpp::Function key_callback) {

  key_callback_func_ptr = std::make_unique<Rcpp::Function>(key_callback);
  glfwSetKeyCallback((GLFWwindow*)window, (GLFWkeyfun) glfw_set_key_callback_wrapper);

}

编辑

下面的编译功能glfw_destroy_window并将其导出为glfwDestroyWindow的源代码使用类型GLFWwindow_ptr并从R编译并正常工作。

glfwDestroyWindow.cpp

#include "glfw_types.h"
using namespace Rcpp;

//' @export
// [[Rcpp::export("glfwDestroyWindow")]]
void glfw_destroy_window(GLFWwindow_ptr window) {
  glfwDestroyWindow((GLFWwindow*)window);
  R_ClearExternalPtr(window);
}

编辑2

此功能也可以正常工作：

#include "glfw_types.h"
using namespace Rcpp;

//' @export
// [[Rcpp::export("glfwCreateWindow")]]
GLFWwindow_ptr glfw_create_window(int width, int height, std::string title) {
  const char *title_c = title.c_str();
  return GLFWwindow_ptr(glfwCreateWindow(width, height, title_c, NULL, NULL), true);
}

编辑3

这似乎正在起作用...

新的glfw_set_key_callback.cpp

#include "glfw_types.h"
using namespace Rcpp;

namespace {
  std::unique_ptr<Rcpp::Function> key_callback_func_ptr;
}

void glfw_set_key_callback_wrapper(GLFWwindow* window, int key, int scancode, int action, int modes)
{
  (*key_callback_func_ptr)(GLFWwindow_ptr(window, true), key, scancode, action, modes);
}

// [[Rcpp::export]]
void glfw_set_key_callback(GLFWwindow_ptr window, Rcpp::Function key_callback) {

  key_callback_func_ptr = std::make_unique<Rcpp::Function>(key_callback);
  glfwSetKeyCallback((GLFWwindow*)window, (GLFWkeyfun) glfw_set_key_callback_wrapper);

}

非常感谢您的帮助！

Answer 1

#include "glfw_types.h"
using namespace Rcpp;

namespace {
  std::unique_ptr<Rcpp::Function> key_callback_func_ptr;
}

void glfw_set_key_callback_wrapper(GLFWwindow* window, int key, int scancode, int action, int modes)
{
  (*key_callback_func_ptr)(GLFWwindow_ptr(window, false), key, scancode, action, modes);
}

// [[Rcpp::export]]
void glfw_set_key_callback(GLFWwindow_ptr window, Rcpp::Function key_callback) {

  key_callback_func_ptr = std::make_unique<Rcpp::Function>(key_callback);
  glfwSetKeyCallback((GLFWwindow*)window, (GLFWkeyfun) glfw_set_key_callback_wrapper);

}