sol2/examples/source/overridable_function_members.cpp

#define SOL_ALL_SAFETIES_ON 1
#include <sol/sol.hpp>

#include <iostream>

int main() {
	std::cout << "=== override-able member functions ==="
	          << std::endl;

	struct thingy {
		sol::function paint;

		thingy(sol::this_state L)
		: paint(sol::make_reference<sol::function>(
		     L.lua_state(), &thingy::default_paint)) {
		}

		void default_paint() {
			std::cout << "p" << std::endl;
		}
	};

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

	lua.new_usertype<thingy>("thingy",
	     sol::constructors<thingy(sol::this_state)>(),
	     "paint",
	     &thingy::paint);

	sol::string_view code = R"(
obj = thingy.new()
obj:paint()
obj.paint = function (self) print("g") end
obj:paint()
function obj:paint () print("s") end
obj:paint()
)";

	lua.safe_script(code);

	std::cout << std::endl;

	return 0;
}