#define SOL_ALL_SAFETIES_ON 1

#include <sol/sol.hpp>

#include <memory>

#include <iostream>

struct Shape {

virtual ~Shape() = default;

};

struct Box : Shape { };

SOL_BASE_CLASSES(Box, Shape);

SOL_DERIVED_CLASSES(Shape, Box);

int main() {

sol::state lua;

lua.open_libraries(sol::lib::base);

lua.new_usertype<Shape>("Shape", sol::no_constructor);

lua.new_usertype<Box>("Box", sol::factories([&]() {

auto b = std::make_shared<Box>();

std::cout << "create Box@" << std::hex << b.get()

<< '\n';

return b;

}));

lua.set_function(

"inspect_shape_table", [](const sol::table& args) {

std::shared_ptr<Shape> defbox = nullptr;

// check if there's a field with the name "shape"

auto s = args.get<

sol::optional<std::shared_ptr<Shape>>>(

"shape");

std::cout << "has : " << std::boolalpha

<< s.has_value() << '\n';

// get the field named "shape" or use the default

// value

std::cout << "get_or: " << std::hex

<< args.get_or<std::shared_ptr<Shape>>(

"shape", defbox)

.get()

<< '\n';

// this works but I can't test for existence

// beforehand...

std::cout

<< "get : " << std::hex

<< args.get<std::shared_ptr<Shape>>("shape")

.get()

<< '\n';

});

sol::protected_function_result result = lua.safe_script(

"inspect_shape_table({shape=Box.new()})");

sol_c_assert(result.valid());

return 0;

}