How would I make a C-function that I can call from Lua?

Question

I would like to know how to make a C-function and be able to tell Lua about it, then call it from Lua. I have all the Lua Libraries installed on my Mac OSX 10.4 computer.

Answer 1

There's an excellent example of Lua-C integration here and here.

If you just need to export a function into the global namespace, then:

1. Declare the function (let's call it f) with signature lua_CFunction.
2. Call lua_register(L, "myfunc", f), with L being the Lua state, and function = f.
3. Run the lua code. Then f will be available in the global namespace as myfunc.

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If you're going to use the stock interpreter then you might want to make a library. This guy wrote an article for Lua Programming Gems that explains how to do it. The sources are available online.