Safely pass LUA sequences to C++ using Sol2

Question

I am using Sol2 to bridge between Lua and C++ code. I would like to pass sequences of numbers from Lua to C++.

From Lua:

func{3, 2, 1.5, 10}

In C++:

void func(std::vector<double> v)
{ ... }

What is the best way to connect the call with the C++ function?

If I directly bind the C++ function I get a segfault. I think I can write a function that converts a sol::table to a std::vector<double>, throwing exceptions if there are any mismatched types, but I'm not sure the best way to do this or if this is the right direction to go.

Answer 1

Here is one solution:

/**
 * Convert a Lua sequence into a C++ vector
 * Throw exception on errors or wrong types
 */
template <typename elementType>
std::vector<elementType> convert_sequence(sol::table t)
{
    std::size_t sz = t.size();
    std::vector<elementType> res(sz);
    for (int i = 1; i <= sz; i++) {
        res[i - 1] = t[i];
    }
    return res;
}

This manually converts the sol::table into a std::vector and copies each element one by one. It errors if any elements in the table have the wrong type, or if things are missing.