Re: XML structured script output (storing results per script instance)

[David Fifield <david () bamsoftware com>]

On Tue, Jul 31, 2012 at 10:14:48PM -0400, Patrick Donnelly wrote:
> On Jul 31, 2012 9:08 PM, "David Fifield" <david () bamsoftware com> wrote:
> > Daniel's structured output branch stores the output of a script as a Lua
> > object in the Lua registry, in a table keyed by "NSE_SCRIPT_RESULT"] and
> > subkeyed by the pointer to the script instance.
>
> Why would you store it in the lua registry?
>
> > Here's an excerpt from
> > ScriptResult::set_output:
> >
> >   key = lua_topointer(L, pos+1);
> >   lua_getfield(lstate, LUA_REGISTRYINDEX, NSE_SCRIPT_RESULT); /* -3 */
> >   lua_pushfstring(lstate, "%p", key); /* -2 */
> >   lua_pushvalue(lstate, pos); /* -1 */
> >   lua_settable(lstate, -3); /* _R[NSE_SCRIPT_RESULT][key] = return_value
> */
> > Lua experts: is this the usual way to accomplish this? Is it safe to
> > rely on addresses in this way?
>
> No and maybe.

So what's the recommended way to do this? Previously set_output
immediately converted a Lua string to a std::string, with no need to
hold on to a lua_State. Now set_output can receive more generally a
table, which I suggested keeping in the Lua registry rather than
converting to a C++ representation of the same table.

David Fifield
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