Lua Native Function

Last updated on 2020-12-22

Lua is unique, its simple to setup, simple to learn, and simple to bind, most embedable scripting languages fail at least one of these.

I don’t cover building Lua as its trivial, you don’t need any special build flags, if you are on macOS you can use brew.

brew install lua

Linux will have similar, Windows errr … yeah anyway.

Call a native function…

/* lua.c */
#include <lua/lua.h>
#include <lua/lualib.h>
#include <lua/lauxlib.h>
#include <stdio.h>


int
native_wrapper(lua_State *L) {
        int arg_count = lua_gettop(L);

        if(arg_count) {
                printf("%s\n", lua_tostring(L, 1));
        }

        return 0; /* number of returns */
}

void
lua_native_function(lua_State *L) {
        const char * script_b = "native_func(\"Lua to Native\")";
        lua_register(L, "native_func", native_wrapper);
        luaL_dostring(L, script_b);
}


int
main() {
        lua_State *L = luaL_newstate();
        luaL_openlibs(L);

        lua_native_function(L);

        lua_close(L);

        return 0;
}

Outputs …

Lua to Native

Build and run …

clang lua.c -I /usr/local/include -L /usr/local/lib -llua && ./a.out