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Good point about the error handling.
I thought about this too, but unfortunately I found the topic to be too complex to reasonably fit into the time available for such a talk. In later Lua versions you can compile the source as C++ code and configure it to use exceptions instead of longjmps, but I would already consider that a fairly advanced topic.

Thank you all for the kind words and the very valuable suggestions!

Best regards,

On 10/31/2017 10:07 AM, Kevin Martin wrote:

I thought it was a really good presentation. I really like the call function as I can see that it would simplify a lot of our code.

On 30 Oct 2017, at 21:05, Andreas Weis <> wrote:

If you feel that I gravely misrepresented some aspect of the language or
you think that there is something that is clearly missing from the
presentation, I will gladly take your advice into consideration.

One thing that comes to mind is our biggest pain point, which is error handling. I have found very little guidance on mixing c++ exceptions and Lua.

We compile Lua as C (because we don’t really understand LUAI_THROW/LUAI_CATCH and how they mix with our own exceptions). Our understanding is that if we’re inside a C++ function, and a lua api function errors, our destructors won’t be called because it will longjmp to the nearest pcall. The most common example is calling lua_gettable on something with an __index metamethod - as there is no way to know prior to trying the gettable that the metamethod will fail.

At the moment we wrap all our code in try/catch blocks and translate any c++ exceptions to lua errors, we use lua_pcall instead of lua_call, and from the lua side, we try to ensure that nothing else can error while we’re inside a try block and there are objects that need destructors called.