How can I fail a function without throwing exceptions?

[GasimGasimzada]

Assuming I have a function like this:

sol::state_view state(luaState);

state["test_fn"] = [](bool value) {
  if (!value) {
    // How can fail here without throwing exception?
  }
};

How can I fail this function?

[Rochet2]

Hmm. I don't think sol has an error mechanism like that. And calling lua's error functions would not clean up any objects that sol has created I think as it would do longjmp.

What is the usecase? Why not use exception?

[glebm]

We have the same issue as our codebase has exceptions disabled. One convoluted workaround is to return a string with the error message and call error on the Lua side if the result is a string.

[glebm]

Ideally, sol would be integrated with std::expected (or tl::expected) so that the lamba could just return an expected<T, std::string> and sol would handle the unwrapping and calling Lua's error.