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On 5/12/2011 2:09 AM, steve donovan wrote:
On Thu, May 12, 2011 at 11:01 AM, KHMan<keinhong@gmail.com> wrote:Eh, my memory cells is a failure, a C preprocessor in Lua is probably more like a 40KB stripped binary chunk. But it's under 20KB without the #if* conditional syntax and expression parsing. There is quite a lot to implement...Oh yes, that's the complicated bit! Although does it make sense to expect a Lua FFI package to read implementation C header files? They are clunky and often depend on lots of little bits. Much better to have a tool to massage them and extract exactly what one wants, and include that. Such a tool could start out by using the standalone C preprocessor as a first step. Then (for instance) the target system only needs foo, not foo-dev steve d.
Take for example the simplest "struct dirent" - I needed opendir, closedir, readdir etc. for my linux/osx machines, and wanted to use through FFI - but the structure is different for each os, then architecture, and even compilation mode (_POSIX_SOURCE or whatever there is).
Now for GCC there was a way to tell the preprocessor to spit all of it's predefined macros, but for MSVC there is no way, unless you know what macros are there (for example _WIN32, _MSC_VER, etc.)
On top of that, system header files being totally compiler dependent they can contain things that are not even C (for example MSVC's SAL mechanisms, uuids, etc.).
For that reason I'm still sticking to FFI, but looking for libs, that are sanely written with same structures everywhere for every architecture, or even if they are different, at most I can just say if ffi.os == "Windows" then ffi.cdef("one way") else ffi.cdef("another way") end