Thoughts wanted on automatically "wrapping" existing functions.

[Matthew Burke <matthew@...>]

First a little background:

I often use Lua-GD because in many cases,  I find it easier to create an 
image by writing code than to try and draw it.

Recently I came up with an idea to make the process a little more 
interactive, and to type less. I've tried it out with just a small 
handful of the functions and I like how it's shaping up.

Here's the essence of the idea:

gd = require 'gd'

local _img
local _file = os.tmpname()

function show()
   _img:png(_file)
   os.execute('open -a Preview ' .. _file)
end

function create(sx, sy)
   _img = gd.create(sx, sy)
   --
   -- some code to create a set of colors...
   ---
end

function setpixel(x, y, c)
   local result = _img:setPixel(x, y, c)
   show()
   return result
end

function rectangle(x1, y1, x2, y2, c)
   local result = _img:rectangle(x1, y1, x2, y2, c)
   show()
   return result
end

-- etc, etc


Now for my question:

I could write the "wrapper" functions by hand. There are roughly 130 
functions and constants in Lua-GD, so it wouldn't take forever. But I 
feel like there's some clever way I'm not seeing to do it more 
automatically.

Another possibility is to change the C code that implements the library. 
But I'd prefer to leave it intact.


Here are a couple of issues with doing it automatically:

- debug.getInfo tells me that all the functions are vararg so I can't 
build a parameter list

- if I build up the wrapped function as a string and then pass it to 
load() to create, since _img is local, I get an error about it being nil 
when I try and invoke the function.



So I could easily crank this out by hand and already be done. But I'd 
like to hear any suggestions on what's a more clever approach.