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I was under the impression that the stack has a certain size (say, 20, defined when the lua lib is compiled), and that gettop just returns the index of the top-most element on that stack. So if top=10, an index is still acceptable if it refers to 11, but not if it refers to 21. Is this defined rigorously anywhere? 
Oliver

On Tue, Aug 30, 2011 at 10:58 AM, Robert Raschke <rtrlists@googlemail.com> wrote:

On Tue, Aug 30, 2011 at 3:52 PM, Robert Raschke <rtrlists@googlemail.com> wrote:

On Tue, Aug 30, 2011 at 3:22 PM, oliver <oliver.schoenborn@gmail.com> wrote:
Would it be correct to say, "all functions which take a stack index
require that it is inside the available stack space", 
...
or when stackspace equals X
   luaL_checkany(L,X+1) is undefined.

BTW, is there a way of knowing "available stack space"? Alternately a "bool lua_isacceptable(L, index)" would be a nice function to have. 
Oliver

int lua_checkstack(lua_State *L, int extra);

http://www.lua.org/manual/5.1/manual.html#lua_checkstack


Actually, on reflection that's not exactly what you're asking for. But lua_gettop (http://www.lua.org/manual/5.1/manual.html#lua_gettop) gets you the size of the stack. So these two give you what you need, or not?

Robby