Extend Lua with custom C functions using Clang

Here is a boilerplate for extending Lua with custom C functions. This requires Clang and Lua 5.1 to be installed. GCC can be used instead of Clang, but the Makefile will need to be modified.

• nativefunc.c

  #include <lua.h>
  #include <lauxlib.h>
  
  static int l_mult50(lua_State *L) {
    double number = luaL_checknumber(L, 1);
    lua_pushnumber(L, number * 50);
    return 1;
  }
  
  int luaopen_nativefunc(lua_State *L) {
    static const struct luaL_Reg nativeFuncLib[] = { {"mult50", l_mult50}, {NULL, NULL} };
  
    luaL_register(L, "nativelib", nativeFuncLib);
    return 1;
  }
  

• main.lua

  require "nativefunc"
  print(nativelib.mult50(50))
  

• Makefile

  CC       = clang
  CFLAGS   =
  INCLUDES = `pkg-config lua5.1 --cflags-only-I`
  
  all:
    $(CC) -shared -o nativefunc.so -fPIC nativefunc.c $(CFLAGS) $(INCLUDES)
  
  clean:
    rm *.so