lua_getfield
lua_getfield(L, -1, modname); /* get _LOADED[modname] */
lua_getfield(L, idx, fname);
#define luaL_getmetatable(L,n) (lua_getfield(L, LUA_REGISTRYINDEX, (n)))
lua_getfield(L, -1, "unpack");
LUA_API void (lua_getfield) (lua_State *L, int idx, const char *k);
lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
lua_getfield(state, 1, kwargs[i].za_name);
lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);