sol2/examples/functions.cpp

90 lines
2.4 KiB
C++

#include <sol.hpp>
#include <cassert>
inline int my_add(int x, int y) {
return x + y;
}
struct multiplier {
int operator()(int x) {
return x * 10;
}
static int by_five(int x) {
return x * 5;
}
};
inline std::string make_string( std::string input ) {
return "string: " + input;
}
int main() {
sol::state lua;
lua.open_libraries(sol::lib::base);
// setting a function is simple
lua.set_function("my_add", my_add);
// you could even use a lambda
lua.set_function("my_mul", [](double x, double y) { return x * y; });
// member function pointers and functors as well
lua.set_function("mult_by_ten", multiplier{});
lua.set_function("mult_by_five", &multiplier::by_five);
// assert that the functions work
lua.script("assert(my_add(10, 11) == 21)");
lua.script("assert(my_mul(4.5, 10) == 45)");
lua.script("assert(mult_by_ten(50) == 500)");
lua.script("assert(mult_by_five(10) == 50)");
// using lambdas, functions could have state.
int x = 0;
lua.set_function("inc", [&x]() { x += 10; });
// calling a stateful lambda modifies the value
lua.script("inc()");
assert(x == 10);
// this can be done as many times as you want
lua.script("inc()\ninc()\ninc()");
assert(x == 40);
// retrieval of a function is done similarly
// to other variables, using sol::function
sol::function add = lua["my_add"];
int value = add(10, 11);
assert(add.call<int>(10, 11) == 21);
assert(value == 21);
// multi-return functions are supported using
// std::tuple as the interface.
lua.set_function("multi", [] { return std::make_tuple(10, "goodbye"); });
lua.script("x, y = multi()");
lua.script("assert(x == 10 and y == 'goodbye')");
auto multi = lua.get<sol::function>("multi");
int first;
std::string second;
std::tie(first, second) = multi.call<int, std::string>();
// use the values
assert(first == 10);
assert(second == "goodbye");
// you can even overload functions
// just pass in the different functions
// you want to pack into a single name:
// make SURE they take different number of
// arguments/different types!
lua.set_function("func", sol::overload([](int x) { return x; }, make_string, my_add));
// All these functions are now overloaded through "func"
lua.script(R"(
print(func(1))
print(func("bark"))
print(func(1,2))
)");
}