Re: Current state of 5.1, and the PS2.

[Rici Lake <lua@...>]

On 2-Nov-06, at 9:39 PM, Glenn Maynard wrote:

> Anyhow, a "lua_checkfunctionenv(L)" function to throw an error if L is
> not in a Lua C call could prevent "didn't call through Lua" from being 
> a
> lurking bug.

It's not going to lurk, by the way. In my experience, it simply 
segfaults when you call luaopen_io. It might be nice to have a better 
error message :) but I don't believe that it will leave any sort of 
lurking poisoned chalice about. I could be wrong, though... I haven't 
tested it on more than a few systems, and that accidentally.

If you just use luaL_openlibs() from linit.c, customising the library 
list according to your needs, then you avoid the whole problem. (Or if 
you create a custom version which accepts a luaL_Reg structure as a 
second parameter.) Assuming that the library writers don't follow my 
advice and do pollute the global namespace with their libraries.

I think the following will implement the function you're looking for:

lua_Debug ar;
if (lua_getstack(L, 0, &ar) = 0) {
  printf("No call frame available");
  exit(1);  /* Can't call lua_error() */
}