protect

routine to mark a function / variable as requiring safety

template <typename T>
auto protect( T&& value );

sol::protect( my_func ) allows you to protect a function call or member variable call when it is being set to Lua. It can be used with usertypes or when just setting a function into sol. Below is an example that demonstrates that a call that would normally not error without Safety features turned on that instead errors and makes the Lua safety-call wrapper pcall fail:

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

#include "assert.hpp"

int main(int, char*[]) {

	struct protect_me {
		int gen(int x) {
			return x;
		}
	};

	sol::state lua;
	lua.open_libraries(sol::lib::base);
	lua.new_usertype<protect_me>("protect_me", 
		"gen", sol::protect( &protect_me::gen )
	);

	lua.script(R"__(
	pm = protect_me.new()
	value = pcall(pm.gen,"wrong argument")
	)__");
	bool value = lua["value"];
	c_assert(!value);

	return 0;
}