Turn runnable code into property objects [Example with GLFW window]

window_properties.cpp

#include <cstdio>
#include <utility>
#include <GLFW/glfw3.h>
#include <unistd.h>

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) {}
static void error_callback_glfw(int error, const char* description) {}
static void framebuffer_size_callback(GLFWwindow* window, int width, int height) {}


struct BasicProperties {
  int width;
  int height;
  const char* title;
};

auto KeyCallback(GLFWkeyfun keyfun) {
  return [keyfun](GLFWwindow* window) {
    glfwSetKeyCallback(window, keyfun);
  };
}

auto FramebufferSizeCallback(GLFWframebuffersizefun cb) {
  return [cb](GLFWwindow* window) {
    glfwSetFramebufferSizeCallback(window, cb);
  };
}

auto MakeContextCurrent() {
  return [](GLFWwindow* window) {
    glfwMakeContextCurrent(window);
  };
}

class Window {
public:
  template<typename ...Props>
  static Window with_properties(BasicProperties basics, Props&&... props) {
    Window window(basics);
    (props.operator()(window.m_window), ...);
    return window;
  }

private:
  Window(BasicProperties basics) {
    m_window = glfwCreateWindow(basics.width, basics.height, basics.title, NULL, NULL);
    if (!m_window) {
      fprintf(stderr, "Window or OpenGL context creation failed.\n");
    }
  }

private:
  GLFWwindow* m_window;
};

////////////////////////////////////////////////////////////////////////////////

int main()
{
  if (!glfwInit()) {
    fprintf(stderr, "GLFW initialization failure.\n");
    return 2;
  }
 
  auto window = Window::with_properties(
      BasicProperties{ .width=1280, .height=720, .title="Graphics Programming" },
      KeyCallback(key_callback),
      FramebufferSizeCallback(framebuffer_size_callback),
      MakeContextCurrent()
  );

  sleep(2);

  glfwTerminate();
  return 0;
}