Initializing Lua state in C

Question

I'm trying to use Lua (5.2) from my C code. I'm creating a Lua state and calling "luaL_openlibs", but global function such as "loadstring" aren't initialized.

lua_State* L = luaL_newstate();
luaL_openlibs(L);
luaL_loadstring(L, "print(loadstring)");
lua_pcall(L, 0, LUA_MULTRET, 0);

Result is: nil. Simple Lua code works (for example, print("hello")), so does the standard libs (strings, ...). Please help me to figure out what am I doing wrong, i've been searching google for a couple of hours and all I found were those weird old mail-lists and Lua documentation (which is also not very helpful, IMO).

Thanks.

Answer 1

Ok, found this in the comments:

@@ LUA_COMPAT_LOADSTRING defines the function 'loadstring' in the base
** library. You can rewrite 'loadstring(s)' as 'load(s)'.

So after defining that const I could use "loadstring" :)

Answer 2

The reference manual is always very useful. As you can see in the table at the bottom, there is no loadstring in Lua 5.2, the closest is load . Also if you check section 8.2 of that manual, Changes in the Libraries , you can see an item regarding loadstring that was available in 5.1, saying incidentally that loadstring has been replaced by load , same functionality.

Changing the source should always be a last resort ie only if there is no other way. Here, what you want is easily doable via the C API:

lua_getglobal(L, "load")
lua_setglobal(L, "loadstring")

Even in cases where you don't use C (just straight Lua), you can do loadstring = load at the top of the script. Or setenv LUA_INIT "loadstring=load" in a console or .bashrc , then Lua executes this for every script it runs (from that console). Or run your script as lua -e'loadstring=load' yourScript.lua . Am I missing any? :)