#define SOL_ALL_SAFETIES_ON 1 #include int main () { struct callable { int operator()( int a, bool b ) { return a + (b ? 10 : 20); } }; sol::state lua; // Binds struct as userdata // can still be callable, but beware // caveats lua.set( "not_func", callable() ); // Binds struct as function lua.set( "func", sol::as_function( callable() ) ); // equivalent: lua.set_function( "func", callable() ); // equivalent: lua["func"] = callable(); }