Re: WxLua and require

["John Labenski" <jlabenski@...>]

On 5/9/06, Diego Nehab <diego@tecgraf.puc-rio.br> wrote:
> > Is there a *simple* C library that shows an implementaion of the C
> > side of this. I've looked at some of the ones on LuaForge, but they
> > use a compat51 script which I'd rather avoid and just do it the 5.1
> > way. Of course maybe I'm not understanding what compat51 is really
> > doing...
>
> I am setting one up for you just now.
>      http://www.cs.princeton.edu/~diego/ran2.tar.gz
>
> Let me know when you get it and I will remove the file.

Thanks alot, that is a very nice example! I thought it was really that
simple, but I wasn't sure.

All you need is this single function right?

int luaopen_ran2(lua_State *L) {
  do whatever you want here
  return 1;
}

Must you always return 1? wxLua doesn't use the luaL_openlib(L,
"ran2", ran2_func, 1) method of creating the lib since it's a little
more complicated and we have to worry about setting up metatables for
tracking objects. I suppose that I could just push the global "wx"
table we create onto the stack after wxLua does it's thing and nobody
would be any the wiser right?

Just to be sure, if I understand the code in lua/src/loadlib.c, Lua's
require takes "require"XXX"" and looks for the C function
"luaopen_XXX" in the library and runs it. You have to name the
"-shared" library XXX.so for lua to find and you also need "-fpic" for
the position-independent code in the library. This last bit would have
certainly caused me a headache as I wouldn't have thought to do that.

> Don't worry about compat-5.1. This is what Lua 5.0 people
> have to use to have access to the Lua 5.1 package system.
> The interface is exactly what you would find in Lua 5.1. Of
> course, if you are using Lua 5.1, you already have that.

I wasn't really sure if it was that the C code was written for 5.1 and
compat51 tricked lua50 to work properly or if it was the other way
around.

Thanks again, I'll give it a shot later this week, when the
SourceForge CVS is back up :(
  John Labenski