Re: building module on OSX

[Ryan Raaum <ryan@...>]

> Hi,

Hi,

> I'm trying to build a dynamic library module on OSX that I can then
> load with require().  Lua finds the dylib, but when it tries to load I
> get the error "hello.dylib:1 unexpected symbol near ',' ".  Why does
> it try to give me a line number for a compiled binary?  Anyone have
> this problem before?
>
> thanks,
> wes

Assuming you have built Lua 5.1.1 from the standard tarball via "make  
macosx", the simplest possible binary extension build process goes  
something like this (modify for your directory setup). Create a file  
"mylib.c" in the distribution src/ directory with:

#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
#include "math.h"

static int l_cos (lua_State *L);

static const struct luaL_reg mylib [] = {
    {"cos", l_cos},
    {NULL, NULL}  /* sentinel */
};

static int l_cos (lua_State *L) {
    double d = lua_tonumber(L, 1);  /* get argument */
    lua_pushnumber(L, cos(d));  /* push result */
    return 1;  /* number of results */
}

int luaopen_mylib (lua_State *L) {
    luaL_openlib(L, "mylib", mylib, 0);
    return 1;
}

then build this with:

gcc -O2 -fno-common -c -o mylib.o mylib.c
gcc -bundle -undefined dynamic_lookup -o mylib.so mylib.o

test by starting the lua interpreter and:

require("mylib")
=mylib.cos(1)

Best,

-r