Breaking change in 3.0-rc6 with multiple returned results from call

[AnyPioneer]

int NodeWithLua::hook_goto() {
  auto hook = "hook_goto";
  luabridge::LuaRef table = luabridge::getGlobal(L, _tableName);

  auto F = table[hook];
  if (!F.isFunction()) {
    // auto s = std::format("{} {} is not a function!", _functionName, hook);
    // std::cerr << s << std::endl;
    // throw std::runtime_error(s);
    return 0;
  }

  auto over = F();
  if (over.hasFailed()) {
    std::cerr << over.errorMessage();
    throw std::runtime_error(over.errorMessage());
  }

  if (over.size() > 0) {
    auto gotoNodeId = over[0].cast<int>().valueOr(0);
    return gotoNodeId;
  }

  return 0;
}

[kunitoki]

We improved the efficiency of returning values from lua function calls in c++. Try using F.call<int>() which returns a TypeResult you can check (or valueOr(0) over it).

[kunitoki]

int NodeWithLua::hook_goto() {
  auto hook = "hook_goto";

  luabridge::LuaRef table = luabridge::getGlobal(L, _tableName);

  auto F = table[hook];
  if (! F.isFunction()) {
    return 0;
  }

  auto over = F.call<int>();
  if (! over) {
    std::cerr << over.message();
    over.throw_on_error();
  }

  return *over;
}

[AnyPioneer]

Thank you for your correction. But how do I accept tables and multiple return values?

[AnyPioneer]

#include <iostream>

#include "lua/LuaWithBridge.hpp"
#pragma comment(lib, "lua/lua54.lib")

#define TEST 1

void f() {
  auto _tableName = "M";
#if TEST == 0
  auto s = R"(
M={
    hook_goto =function()
        return 3
    end
}
)";
#elif TEST == 1
  auto s = R"(
M={
    hook_goto =function()
        return {1,2,3,"four"}
    end
}
)";

#elif TEST == 2
  auto s = R"(
M={
    hook_goto =function()
        return 1,2,3,"four"
    end
}
)";
#endif

  auto L = luaL_newstate();
  luaL_openlibs(L);

  if (luaL_dostring(L, s) != LUA_OK) {
    std::string s(lua_tostring(L, -1));
    std::cerr << "Setup path error: " << s << std::endl;
    lua_pop(L, 1);
    return;
  }

  {
    auto hook = "hook_goto";

    luabridge::LuaRef table = luabridge::getGlobal(L, _tableName);

    if (!table.isTable()) {
      std::cerr << "no table" << std::endl;
      return;
    }

    auto F = table[hook];
    if (!F.isFunction()) {
      std::cerr << "no function" << std::endl;
      return;
    }

    auto over = F.call<int>();
    if (!over) {
      std::cerr << over.message();

      return;
    }

    std::cout << "r:" << *over;
  }
}
int main() {
  try {
    f();
  } catch (const std::exception& e) {
    std::cerr << e.what() << std::endl;
  }

  return 0;
}

[kunitoki]

You can get:

1 value = F.call<int>()
2 values = F.call<std::tuple<int, float>>()
table = F.call<luabridge::LuaRef>()

[AnyPioneer]

Thank you very much, expert!

[AnyPioneer]

hook_goto1 =function()
    return 1,{2, "three"}
end

auto r = F.call<std::tuple<int,luabridge::LuaRef>>();

[AnyPioneer]

std::tuple<int, luabridge::LuaRef>
No suitable default constructor is available.

I can't compile it. Please help me .

[kunitoki]

This is a bug in LuaBridge3, should be fixed in #222