Wednesday, November 25, 2009

SWIG and Lua

So I've been trying out SWIG with Lua recently. This was to wrap a 3rd party C library that I didn't have source for.

The initial wrapping went pretty smoothly. The only problem was that the library had its own typedef of 'bool' as an unsigned char, but SWIG treated that as a syntax error. I had hoped to avoid making copies of the header files, but ended up doing that and so commented out the typedef.

I was also a bit disappointed with the handling of some pointer types. Suppose you've got a function that takes a pointer to a double. I had expected that I could just call the wrapped Lua function with a Lua number and have that handled automatically. But I ended up declaring some pointer types, creating those C-based objects, and using those. There is some means with SWIG to declare pointer args, but I need to read that section of the docs again.

Similarly, I wanted to just pass in a table of strings and have that automatically converted to 'char **', but that is not automatic either. So that code on the Lua side is klunky too. I'm not sure that can be fixed.

I'll have to investigate luabind and toLua more.

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